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CHEMICAL COMBINATION 
AMONG METALS 


CHEMICAL COMBINATION 
AMONG METALS 


BY 


DR. MICHELE GIUA 


PROFESSOR OF GENERAL CHEMISTRY IN THE ROYAL UNIVERSITY OF SASSARI 
AND 


DR. CLARA GIUA-LOLLINI 


AWARDED THE PRIZE OF THE CAGNOLA FOUNDATION BY THE 
ROVAL LOMBARDY INSTITUTE OF SCIENCE AND LITERATURE 


TRANSLATED BY 


GILBERT WOODING ROBINSON 


ADVISER IN AGRICULTURAL CHEMISTRY, UNIVERSITY COLLEGE, BANGOR 


PHILADELPHIA 
Po BK PONS SON oa AO. 


1012, WALNUT STREET 
1918 


Printed in Great Britain. 


EC REEPACE. 


Tue subject of chemical combination among metals is of 
considerable interest and importance in general chemistry. 
Viewing the recent developments of the chemistry of metals, 
we cannot fail to remark the immense strides made in little 
less than a score of years. This progress has been made 
possible by the rapid and incessant development of modern 
metallography. To give a historical picture would involve 
the detailed discussion of almost all the problems around 
which metallography is grouped. 

The chemistry of metals has been largely studied by means 
of thermal analysis, and it may be fairly said that the subject 
has only acquired clearness since the introduction of 
Tammann’s thermal method, dating from the beginning of 
the present century and still growing steadily in value and 
importance. In our treatment of the subject of the capacity 
of metals for combination with each other this method of 
investigation will be outlined. 

The groundwork of any treatise which aims at explaining 
the nature of chemical combination among metals must be 
that part in which are described the various states of 
equilibrium which can be examined by quantitative methods 
and are, in consequence, susceptible of scientific interpreta- 
tion. The foundation of the various methods used for 
defining the conditions of thermal equilibrium is Gibbs’ 
Phase Rule. 

In the development of our subject we shall proceed, after a 
brief account of the various types of equilibrium diagram for 
binary systems, to define the nature of intermetallic combina- 
tion. ‘This is a matter of considerable difficulty but of great 


vs PREFACE. 


interest. With it is bound up the question of chemical 
compounds of variable composition, recently thrown into new 
light by the fundamental work of the Russian chemist 
Kurnakoff. This part of the subject forms, indeed, a fine 
memorial to the memory of the great Berthollet, whose 
figure ever retains the character of modernity. It is the 
distinctive mark of a genius that he anticipates by many 
years the developments of philosophic or scientific thought 
and leaves, thereby, a deep mark on the hard rocks of science 
—a safe guide to succeeding generations. 

There has been a lack, up to the present, of a complete 
collection of all the binary systems in which intermetallic 
chemical compounds appear. The chapters on ‘‘ Homo- 
polar intermetallic compounds’ and “ Heteropolar inter- 
metallic compounds” now fill this gap. All the studies 
made up to 1915 have been collected and every system has 
been discussed, above all, with reference to the various phases 
of equilibrium which are observed in the fusion of metals. 

With this latter account one may say that the develop- 
ment of the work is complete. A short chapter at the end 
on ternary combinations gives an idea of this as yet little- 
known field of research. So far the investigations on ternary 
combinations are few in number and not even completely 
worked out, but they are enough to claim the attention of the 
student of this branch of the chemistry of the metals. 

An experimental contribution attempts at an investiga- 
tion of the degree of dissociation of intermetallic compounds, 
a subject hitherto untouched, but which serves to give a 
clearer interpretation of the nature of these combinations. 
Mendelejeff’s and Meyer’s classification of the elements, 
together with the thermal method, have afforded a safe guide | 
in the development of the subject. 

The subject of chemical combination among metals has 
been considerably elucidated by the application of physical 
methods to the study of metallic alloys. A complete, 
though summary, description is therefore necessary of the 


PREFACE. } vil 


physical properties of those alloys in which chemical com- 
pounds are formed. This task has also been attempted. 
An extended historical account of the subject has not 
been traced for various reasons. Above all, this branch of 
chemistry is still rather in fieri than in esse, and is not com- 
plete in its various branches. In addition, an account of the 
development of metallography would be needed, which has 
already been ably traced elsewhere.t We have, therefore, 
in the chapter on the nature of intermetallic compounds, 
preferred to confine ourselves to the purely chemical side of 
the history of the subject. 
M. anp C. GIUA. 


? Guertler, Metallographie, Vol. I., Part la, 1912. Desch., Metallography, 1910. 





toe 


ABBREVIATIONS FOR PERIODICALS, ETC. CITED. 


Amer, Journ. of Sci. 
Ann. Chem... 
Ann, Chim. Phys. 
Ann. d. Phys. . 


Ber. ‘ 
Bull. Soc. Chim. 


Bull. Soc. @ Encour. . 


Crelles Journ. . 


Chem. Zentr. . 
Chem. News 
Cok; 


Dingl. Polyt. Journ. . 
De der: 


DD Aor Drud. “Ann. . 
Ferrum . 
Gazz. Chim. Ital. 
Génie Civil 

Gilb. Ann. : 
Int. Z. f. Metall. 
Jahr. ber. 
SEAMS Soe 
Journ. Ch. Ee 
pet ORG: Caer 

J. de Phys. 


Journ. of Phys. “Chem. ; 
J. Russ. Phys. Chem. Soc. . 


Journ. of Science 
Journ. prakt. Ch. 


Journ. Soc. Ch. Ind. 
Mem. Ist. Lombardo . 


Metall. . 
Mon. f. Ch. 
Mon. Scient. 
Nature 

Nuovo Cimento. 
Phil. Mag. 
Phil. Trans. 


Phys. Zeitschr. 
Pogg. Ann, 


Proc. Inst. Mech. Engin. 
Proc. Roy. Soc. of London . 


R. Acc. Lincet . 
Rec. P.-B. 3 ; 


Rend. Acc. Scienze Fis. e Nat. 


Napoli. 


Rend. Soc. Chim. Ital. 


Arch, Pharm. . ‘< 


American Journal of Science. 

Liebigs Annalen der Chemie u. Pharmacie. 

Annales de Chimie et de Physique, Paris. 

Annalen der Physik. 

Archiv der Pharmacie. 

Berichte der deutschen chemischen Gesellschaft. 

Bulletin Société Chimique de Paris. 

Bulletin Société d@ Encouragement, Paris. 

Crelles Journal, Journ. fir die reine und angewandte 
mathematik. 

Chemisches Zentralblatt, Berlin. 

Chemical News, London. 

Compts rendus de ? Academie des Sciences, Paris. 

Dinglers polytechnisches Journal, Berlin. 

Deutsche-Reiche-Patent. 

See Annalen der Physik. 

Ferrum. See Metallurgie. 

Gazzetta Chimica Italiana, Rome. 

Le Génie Civil, Paris. 

Annalen der physik u. der physikalischen Chemie. 

International Zeitschrift fiir Metallographie. 

Jahresberichte der Chemie. 

Journal of American Chemical Society. 

Journal de Chimie Physique, Geneva. 

Journal of the Chemical Society, London. 

Journal de Physique, Paris. 

Journal of Physical Chemistry. 

Journal of the Russian Physico-chemical Society, 
Petrograd, 

See Philosophical Magazine. 

Journal fir praktische Chemie. 

Journal of the Society of Chemical Industrie, London. 

Memorie del R. Istituto Lombardo di Scienze e 
Lettere, Milan. 

Metallurgie. 

Monatshefte fir Chemie. 

Moniteur Scientifique, Paris. 

Nature, London. 

Il Nuovo Cimento, Pisa. 


_ Philosophical M agazine, London. 


Philosophical Transactions of the R. Society of 
London. 

Physikalische Zeitschrift, Leipzig. 

Annalen der Physik u. Chemie. 

Proceedings Institute Mechanical Engineering. 

Proceedings of the Royal Society of London. 

Rendiconti della R. Accademia dei Lincet, Rome. 

Recueil des Travaux Chimique des Pays-Bas, 
Amsterdam, 

Rendiconti Accademia Scienze Fisiche e Naturali, 
Naples. 


Fhe Rendicanti Societa Chimica Italiana, Rome. 


Xx 


ABBREVIATIONS FOR PERIODICALS, ETC. 


Rep. Brit. Ass.. 


Rev. de Métallurgie 

Rev. Génér. des Sciences. 
Trans. Royal Soc. of London 
Verh. K. Ak. Wetensch. Amsterd. 


Wied. Ann. 
Zeit. anorg. Ch. 


39 


- ff. angew. Ch. 


Elektroch.. 


safe DeryatS 


99 


phys. Ch. . 


Report of the British Association for the Advance- 
ment of Science, London. 

Revue de Métallurgie, Paris. 

Revue Generale des Sciences, Paris. 

Transactions of the Royal Society of London. 

Werhandelingen der Koning. Akademie van Weten- 
schappen, Amsterdam. 

Annalen der Physik (Wiedemann). 

Zeitschrift f. anorganische Chemie. 

Zeitschrift f. Elektrochemie. 

Zeitschrift f. angewandte Chemie. 

Zeitschrift f. Krystallographie. 

Zeitschrift f. physikalische Chemie 


CONTENTS. 


PREFACE - 


CHAP TE Rtk 


EQUILIBRIUM DIAGRAMS 
Binary Equilibria 


Class I. (a) The two neu onents find Rees peas com- 
pounds nor solid solutions, 2. (b) The two components are par- 
tially soluble in the liquid state and do not form compounds, 4. 


Class II. The two components form definite compounds, 5. 
(a) The compound melts at a definite temperature to a homo- 
geneous liquid, 6. Abnormal maxima, 7. (b) The compound 
has no definite melting point and decomposes on melting, 9 
(c) The compound is strongly dissociated in the fused state, 11. 

Class III. The two components form solid solutions, 14. 
iyvpecly of Roozepoom, 4. Typeiie 16: Pype- Ilh, 17. 
aypo Lyi, 4d “Pype V.,_18. 


CHAPTER II. 
THERMAL ANALYSIS 


CHAPTER III. 


THE NATURE OF INTERMETALLIC COMPOUNDS 
The Concept of Chemical Combination and the Phase Rule 
Intermetallic Combinations of Variable Composition : 
Intermetallic Compounds and the Theory of Valency anita: S 
Rules) . ; A : é : 
The Degree of Dissociation of Intermetallic Oanipoaads ‘ 
Existence of Intermetallic Compounds in the Vapour State 


CHAPTER IV. 


PHYSICAL PROPERTIES 


Influence exerted by the presence of ii erase Conky, Gani: 
pounds on the physical properties of alloys, 51. Specific Volume, 
52. Specific Heat, 57. Electrical Conductivity, 64. Matthies. 
sen’s Rule, 66. Barus’ Rule, 67. Magnetic Properties, 70. 
Electrolytic Potential, 73. Thermo-electric Power, 81. Thermal 
Conductivity, 84. Thermal Dilatation, 86. Hardness, 89. 
Variation of Hardness with the Composition of Alloys, 90. 
Compressibility, 97. Crystalline Form of Binary Compounds, 99. 
Natural Intermetallic Compounds, 101. 


PAGE 


20 


23 
23 
26 


34 
39 
48 


51 


xl CONTENTS. 


CHAPTER VY. 
PAGE 
HOMOPOLAR INTERMETALLIC COMPOUNDS . ‘ + 105 
Compounds of Elements of Group I. with each other 105 


Ist sub-group, 105, Na-K, 105. 2nd sub-group, 106. Na- 
Au, 106. 


Compounds of Elements of Group II. with each other. [7.108 
Ist sub-group, 108. 2nd sub-group, 108. Mg-Zn, 108. 

Mg-Cd, 109. Hg-Mg, 110. Hg-Ca, 112. Hg-Sr, 112. Hg- 

Ba, 112. Compounds of Calcium with members of 2nd sub- 

group, 113. Ca-Mg, 113. Ca-Zn, 114. Ca-Cd, 115. 


Compounds of Elements of Group IIT. with each other . pee Lee 
Al-La, 117. 
, Compounds of Elements of Group IV. with each other . wee ie by 
Ce:Sn, ili. Ce-Po, 119. 
Compounds of Elements of Group V. with each other. eee Bu!) 
Compounds of Elements of Group VI. with each other |. Ay 
Compounds of Elements of Group VII. with each other . > 120 
Compounds of Elements of Group VIII. with each other. 120 


Compounds of Iron, 121. Fe-Co, 121. Fe-Ni, 122. 


Compounds of Metals of Group I. with Metals of other Groups. 123 

Lithium Compounds, 123. Cd, ze. «Lieto. “125. 
Li-Sn, 125. 

Sodium Compounds, 127. Na-Mg, 127. Na-Zn, 127. Na- 
Cd; 129. “NacsHg. 129. Na-Al. tol.  Na-Fiist.  Na-on, £32: 
Na-Pb,.134,. Na-Sb, 135;. Na-Bi, 136: 

Potassium Compounds, 137. K-Zn, 137. K-Cd, 138. K-Hg, 
139; K-Tii40e ‘Kesa, fl KP, 142. Ke -Spy lao. KBr. 143. 

Rubidium Compounds, 144. Rb-Hg, 144. 

Cesium Compounds, 145. Cs-Hg, 145. 

Copper Compounds, 145. Cu-Be, 145. Cu-Mg, 147. Cu-Zn, 
148. Cu-Ca, 151. Cu-Cd, 153. Cu-Hg, 154. Cu-Al, 154. 

’ CwSn, 156. Cua-sb; 158. | 

Silver Compounds, 159. Ag-Mg, 159. Ag-Ca, 161. Ag-Zn, 
162. Ag-Cd, 163. Ag-Hg, 164. Ag-Al, 165. Ag-Sn, 167. 
Ag-Sb, 168. Ag-Mn, 168. Ag-Pt, 169. 

Gold Compounds, 170. Au-Mg,170. Au-Zn.171. Au-Cd, 173. 
Au-Hg,174. Au-Al,175. Au-Sn,175. Au-Pb,177. Au-Sb, 179. 
Au-Mn, 179. 

Compounds of Metals of Group IT. with Metals of other Groups. 180 

Beryllium Compounds, 180. Be-Fe, 180. 

Magnesium Compounds, 181. Mg-Al, 181. Mg-Tl, 182. Mg- 
Sn, 184. Mg-Ce, 184. Mg-Pb, 185. Mg-Sb, 186. Mg-Bi, 187. 
Mg-Ni, 188. 

Calcium Compounds, 190. Ca-Al, 190. Ca-Tl, 191. Ca-Sn, 
192. Ca-Pb, 193. Ca-Sb, 194. Ca-Bi, 194. 

Zine Compounds, 194. Zn-Al, 194. Zn-Sb, 194. Zn-Mn, 195. 
Zn-Fe, 196. Zn-Co, 197. Zn-Ni, 198. 

Cadmium Compounds, 200. Cd-Sn, 200. Cd-Sb, 200. Cd-Cr; 
201. Cd-Fe, 202. Cd-Co, 202. Cd-Ni, 202. 

Mercury Compounds, 203. Hg-Al, 203. Hg-Ga, 204. Hg-In, 
204. Hg-TI, 204. Hg-Sn, 205. Hg-Ce, 206. Hg-Sb, 206. 
Hg-U,206. Hg-Cr, 206. Hg-Mo,207. Hg-Mn,207. Hg-Fe, 208. 
Hg-Co, 208. Hg-Ni, 208. Hg-Pt, 208. 


CONTENTS. 


Compounds of Metals of Group IIL. with Metals of other Groups . 
Aluminium Compounds, 208. Al-Ce, 208. Al-Sb, 210. 
Al-Mn, 211. Al-Fe, 213. Al-Co, 213. AI-Ni, 216. Al-Cr, 217. 
Thallium Compounds, 218. T1-Pb, 218. Tl-Sb, 219. T1-Bi, 
220. TI1-Pt, 222. 


Compounds of Metals of Group IV. with Metals of other Groups . 
Tin Compounds, 223. Sn-Sb, 223. Sn-Bi, 223. Sn-Mn, 224. 
Sn-Fe, 226. Sn-Co, 226. Sn-Ni, 228. Sn-Pt, 230. 
Cerium Compounds, 231. Ce-Bi, 231. Ce-Fe, 233. 


Lead Compounds, 233. Pb-Bi, 233. Pb-Pd, 233. Pb-Pt, 235. 


Compounds of Metals of Group V. with Metals of other Groups 
Antimony Compounds, 236. Sb-Mn, 236. Sb-Fe, 237. Sb-Co, 

238. Sb-Ni, 239. Sb-Pd, 240. Sb-Pt, 242. Sb-Cr, 243. 
Bismuth Compounds, 244. Bi-Mn, 244. Bi-Ni, 246. 


Compounds of Metals of Group VI. with Metals of other Groups . 
Chromium Compounds, 246. Cr-Fe, 246. Cr-Co, 247. 
Cr-Ni, 247. 
Molybdenum Compounds, 248. Mo-Fe, 248. Mo-Co, 248. 
Mo-Ni, 249. 


CHAPTER VI. 
HETEROPOLAR INTERMETALLIC COMPOUNDS 


General Remarks. 


Boron Compounds, 252. B-Fe, 252. B-Ni, 252. 

Carbon Compounds, 254. C-B, 254. C-Al, 254. C-Ti, 255. 
C-0- 250; ©-Cr,250,. C-Mo, 250, “C2W; 255. -C-V, 256. -C-Mn, 
256.. C-Fe, 256.. C-Ni, 256. 

Silicon Compounds, 256. Si-Li, 256. Si-Cu, 256. Si-Mg, 258. 
Si-Ba, 258. Si-Sr, 258. Si-Ca, 258. Si-Ce, 259. Si-Ti, 260. 
Si-Ar..260.. 1-CLh,- 260. SieV;-261. Si-Ta; 262. Si-Cr;.262. 
Si-Mo, 262. Si-W, 262. Si-U, 262. Si-Mn, 262. Si-Fe, 263. Si- 
Co,264. S1-Nt, 265. Si-kw,-267... SI-PE267. Si-Pa, 267. 

Phosphorus Compounds, 267. P-Cu, 267, P-Ag, 268. P-Au, 
268. P-Mg,269. P-Zn,269. P-Cd,269. P-Hg,269. P-Sn, 269. 
P-Bt,- 269, “P-Cr, 269. P-W, 270. P-Mn, 270. P-Fe; 271. 
PCO oe ha cdo Leb Oe we ae (On Ob oe yo Os 

Arsenic Compounds, 275. As-Cu, 275. As-Ag, 276. As-Au, 
276. As-Mg, 276. As-Zn, 276. As-Cd, 277. As-Hg, 278. 
As-Tl, 278. As-Pb, 278. As-Sn,278. As-Mn,279. As-Fe, 280. 
As-Co.28l.- As-Ni,282. As-Pt: 283. 

Sulphur Compounds, 284. S-Rb, 284. S-Cs, 286. S-Cu, 286. 
S-Ag,287. S-Au,287. S-Bi,287. S-In, 288. S-T1,288. S-Sn, 
289. S-Pb, 290. S-As,290. S-Se, 292. S-Mo, 292. S-Mn, 292. 
S-Fe, 293. S-Co, 295. S-Ni, 296. S-Pd, 296. 

Selenium Compounds, 296. Se-Cu, 296. Se-Ag, 297. Se-Zn, 

- 298. Se-Cd, 298. Se-Hg, 298. Se-In, 298. Se-Tl,298. Se-Sn, 
299. Se-Pb, 300. Se-Sb, 301. Se-Bi, 302. Se-Cr, 302. Se-Mn, 
303. Se-Fe, 303. Se-Ni, 303. Se-Co, 303. Se-Pd, 303. Se-Pt, 
303. 

Tellurium Compounds, 303. Te-Cu, 303. Te-Ag, 304. Te-Au, 
305. Te-Zn, 306. Te-Cd, 306. Te-Hg, 307. Te-In, 308. Te-TI, 
308.- “Le-Sn. 309... “Fe-Pb,-310. Te-As, 310. “Te-Sb; 3h. 2e-Bi,; 
slo “PesWec slo. Peps ola. Leoni; clo. Lesh ts ole: 


X11 


PAGE 


208 


223 


236 


246 


251 
251 


XIV CONTENTS. 


CHAPTER VII. 


TERNARY INTERMETALLIC COMPOUNDS . 
General Remarks : : 
Fundamental Types 
Class I. The three components ‘erystallise in the pure state 
without formation of mixed crystals or chemical compounds 
Class II. The three components form mixed crystals but do 
not combine chemically . 
Class III. The three components combine chemically to form 
either binary or ternary compounds : 

Type l. Of the three components, completely miscible in 
the liquid state, two, A and B, form a binary compound 
D, 318. Type cae Of the three components, completely 
miscible in the liquid state, A and B form a compound D, 
and A and C form a compound E, 319. TypelIII. The three 
components are completely miscible in the liquid state, A and 
Bformacompound D, A and C form a compound E, and B 
and C form a compound F, 320. Type lV. The three com- 
ponents form a_ ternary compound, 320. Na-K-Hg, 321. 
Na-Cd-Hg, 321. Mg-Al-Zn, 322. Ag-Au-Te, 324. 


TABLES . 


Melting Points and Moi Weights of the more s fuporeant 
Metals and Metalloids, 326. Periodic System, 327. ane 
Systems studied thermally 

Binary Systems in which Chemical Combinations do not occur 


INDEX OF AUTHORS 
INDEX OF BINARY SYSTEMS 


PAGE 
314 


314 
316 


316 
318 
318 


CHEMICAL COMBINATION 
AMONG METALS. 


CHAPTER I. 


EQUILIBRIUM DIAGRAMS. 


Binary Equilibria. 

Tur application of the principles of the Phase Rule to 
binary systems may now be regarded as almost completely 
elaborated. All the forms of diagram theoretically possible 
have been discussed, and the examples experimentally 
studied have not only corroborated theoretical deductions, 
but have enlarged our view of the subject. The knowledge 
which we possess of the Phase Rule, as applied to the study 
of two-component systems, serves as a guide and help in the 
interpretation of phenomena not only of theoretical but 
also of practical importance. 

All the phenomena encountered in the theoretical and 
experimental study of binary systems may be grouped, 
according to Roberts-Austen, into three general classes. 

Cuass I.—The two components form neither chemical com- 
pounds nor solid solutions. 

Cuass II.—The two components form chemical compounds. 

Cuass I1I.—The two components form solid solutions. 

This classification has a purely systematic value, because 
in reality there are cases in which the components form solid 
solutions to a limited extent and in which, while chemical 
combinations occur, polymorphic transformations exist 
with more or less extended series of mixed crystals and partial 
lack of miscibility. 


C.M. 1 


9° UHEMIGAL [COMBINATION AMONG METALS. 


We may allude to other cases encountered practically : for 
instance, the two components may be completely immiscible 
in the fused state or only miscible to a limited degree. The 
schematic reduction to a few types 18 necessary and sufi- 
cient for the interpretation of the different equilibrium 
diagrams. For our purpose the second and third classes 





EB) 


7 


18) 





2) 





ex 











“S/--- ------------ 





B 
EG la 
alone have a direct importance ; but to make the treatment 
of the subject complete we shall describe all the cases out- 
lined above. 

Cuass I. (a) The two components form neither chemical 
compounds nor solid solutions.—This case is quite simple. 
‘The possible form of equilibrium is shown in Fig. 1. Each of 
the two components 4 and B lowers the melting poimt of 


EQUILIBRIUM DIAGRAMS. 8 


the other so that the curve has two branches meeting in the 
point c¢, the so-called eutectic pomt. This point always lies 
below the melting pots of the components. The liquid 
phase exists in the region above the line ac b, the liquidus 
curve as it is commonly called. The solid phase exists below 
the lne. In the region ace the pure component A separates 
out ; in the region b ce, the pure component B separates out. 
In the region ec A K the pure component 4 exists together 
with the eutectic alloy, while in the region e,¢ B K the pure 
component 5 exists together with the eutectic alloy. 

The phenomena which occur on the solidification of fused 
mixtures of A and B are clearly deduced from the diagram. 
Let us image a fused mixture of composition represented by 
m. On cooling, the pure component A will separate out at 
m and a thermometer immersed in the mixture will show 
slackening in the coolmg curve at the temperature repre- 
sented by that pomt.t| When the mixture cools eventually 
to the point e’, the eutectic alloy separates out. This 
separation is indicated by a further thermometric arrest 
proportional to the content in eutectic alloy of the mixture 
and represented by e’ f’. 

A fused mixture of composition IX, corresponding to that 
of the eutectic alloy, solidifies at the eutectic pomt c. Here 
the thermometric arrest is greater than that for all the 
other possible mixtures of A and B, and is represented by the 
line cf. The region ef e, represents the eutectic arrests for 
all the mixtures comprised in the diagram. 

It should be noted that at the point c the eutectic mixture 
does not solidify homogeneously but is made up of two com- 
ponents. Ifa homogeneous phase solidified at c,it would be | 
a compound, not a mixture. The composition of the 
eutectic alloy does not correspond to any simple molecular 
proportion of the components, or if it does, it is quite 


1 The withdrawal of A from the melt will alter the composition in the direction of B 
and thus the temperature will fall until the eutectic point is reached, when the remain- 
ing mixture of eutectic composition will solidify. 


]l—2 


4 CHEMICAL COMBINATION AMONG METALS. 


fortuitous. The position of the eutectic point depends 
almost always on the melting points of the two components, 
as has been noted by A. Miolati." 

Crass I. (b) The two components are partially soluble im 
the liquid state and do not form compounds.—This case, which 




















-* K > oe 
é ‘i s 
£ - 
| 
\ 
! ' 23 
| ! 
| j 
CU j } 
\ 1 
1 | 
| 
| | 
| 1 
€ | 
me 
\ 
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' ' 
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ye i 9 B 
Fig. 2: 


occurs in certain pairs of metals, is fairly common among 

organic and imorganic compounds. The typical case is that 

of ether and water. The first investigation on organic 

substances partially soluble in water is that of Alexéjeff,” 

who showed that salicylic acid warmed in a closed tube with 

water, in which in the cold it is partially soluble, mixes 
1 Zeit. phys. Chem., 9, 649 (1892). 


2 Journ. prakt. Chem., 133, 518 (1882) ; Bull. soc. chim., 38, 145 (1882); Wied. Ann., 
28, 305 (1886). 


EQUILIBRIUM DIAGRAMS. 5 


with it in all proportions. He has been able to establish 
the fact that between liquids which only mix in limited 
proportions, two solutions are always formed, one of com- 
ponent A in component B, and the others of component B 
in component A, according as one or the other is present in 
creater proportion at the saturation point. 

The equilibrium diagram when the two components A 
and B are completely insoluble in the solid state and 
partially soluble in the liquid state is of the form indicated 
in Fig. 2, in which the liquidus curve is represented by the 
curve aefgb. The horizontal line f g indicates the extent 
of the gap in miscibility. All the liquid mixtures of com- 
position between f’ and g’ consist of two liquid strata, 
namely, the component B and the alloy of composition f’. 
The process of solidification of mixtures of compositions 
lying between f’ and g’ is clearly shown from the diagram. 
Along the line b g, the component B is first deposited, while 
along the line a e, A is first deposited. Along e f, B is 
deposited together with the eutectic alloy. 

W. Spring and Romanoff” have met this case in the study 
of the equilibrium diagrams of lead-zinc and bismuth-zinc. 
Other alloys which show this peculiarity are those of lead- 
nickel, sodium-aluminium, sodium-magnesium, bismuth- 
aluminium, ete. 

This case has been particularly studied by Tammann.’ 

Crass Il. The two components form definite compounds.— 
When chemical combination takes place in the fusion of two 
components the diagram is more complicated ; for our pur- 
pose these curves have the greatest importance. The com- 
pounds formed may have variable conditions of existence 
and yet be more or less stable. 

We shall reduce to three the types of diagrams in 
which definite compounds occur without the formation 


1 H.C. Jones: Elements of Physical Chemistry, p. 179. 
2 Zeit. anorg. Chem., 18, 29 (1896). 
3 Ibid., 47, 293 (1905). 


6 CHEMICAL COMBINATION AMONG METALS. 


of solid solutions between the compounds and the pure 
components. 

(a) The compound melts at a definite temperature to a homo- 
geneous liquid. | 

(b) The compound has no definite melting point and 
partially decomposes on melting. 























b 

/ 
Is sa oh BI ae Sal cC 
reo 

e 
e 
ex @ 
A Am Br B 
Fig. 3. 


(c) 1. The compound is strongly dissociated in the liquid 
state. 2. The compound on fusion forms two liquid strata. 

(a) Let us imagine a case in which, in addition to the 
occurrence of a compound with a definite melting point, the 
three kinds of crystals which exist in the system, 7.e., the 
two components A and B, and the compound 4,, B,, are 
completely soluble in the liquid state and do not form solid 
solutions. The equilibrium diagram then assumes the form 
indicated in Fig. 3. This shows three branches, of which 


HQUILIBRIUM DIAGRAMS. 7 


the middle branch e ¢ e’ indicates the conditions of existence 
of the compound, whose melting point corresponds to the 
maximum ¢ of the curve. The points e and e’ are the two 
eutectics, ¢ being that between the compound and the pure 
component A, and e’ that between the compound and the 
pure component B. In the case indicated in Fig. 3, a fused 
mixture of the components corresponding in composition to 
A,, B, which is allowed to cool, solidifies homogeneously 
and completely at the temperature corresponding toc. The 
fused mixtures of composition e and e’ solidify at the tem- 
peratures corresponding to those points on the diagram and 
show maximal thermometric arrests. ‘The thermal pheno- 
mena which accompany the solidification of mixtures of 
intermediate composition can easily be deduced from what 
has been said above. 

Abnormal maxvma.—tin the study of the antimony- 
aluminium alloys (see Chapter V.) the occurrence of two 
maxima has been observed, without a corresponding 
crystalline form in one of the cases. This second maximum 
is formed, as Tammann has noted! by an abnormal process 
which can be understood from the following considerations. 
The two components A and B (see Fig. 4) are miscible in all 
proportions, but the compound, 4,, B,, forms slowly and 
separates, after sufficiently long heating, along the line e df, 
which is its equilibrium curve. If, however, the melt is not 
heated long enough, then the formation of the compound 
A,, B, is not complete, so that, compared to a melt which 
has been subjected to longer heating, it has a greater content 
of the two components 4 and B. The temperature at which 
crystals of A or B separate out is lower. With an equal 
degree of heating of the various melts the dotted line ae,d, f,) 
gives the temperatures at which A, A,,B, and B separate on 
the respective branches of the curve. If the concentration 
of the melt has become by the separation of crystals of A or B, 


1 Zeit. anorg. Chem., 48, 53 (1906). 


8 CHEMICAL COMBINATION AMONG METALS. 


equal to that indicated by the pot e, there will be three 
kinds of molecules present, namely, A, 4,, B, and B. Since, 
compared to the velocity with which crystallisation takes 
place, the velocity of formation of A,, B, is inconsiderable, 
then, even with the simultaneous separation of A and 4,, B,, 
the concentration of the melt e will alter until at a lower 




















| - 
Ap are 
T 








| | 

| ! 

! 

t ( 
i 

! 








SS -_ 





A ; | AmBn 
Fig. 4. 


temperature than t,, or about t,’ crystals of B will begin to 
separate and the remainder will crystallise at a constant 
temperature with the formation of three kinds of crystals. 
Melts richer in B will behave in a similar manner on cooling. 

Let us consider now the curve e,d,f, : if with increase of 
component A the velocity of formation of the compound 
increases, then the maximum is displaced to dor even a 


RQUILIBRIUM DIAGRAMS. 9 


second maximum is formed. The form that the curve 
assumes depends always on the duration of the heating of 
the melt. As has been said, no conclusions as to the com- 
position of a compound can be drawn from the concentration 
at such a maximum. 

If, before the compound is formed in appreciable quantity, 











C4 gz f 














A Aele oP 


Wee ey is 





the two liquids are immiscible, the phenomena of crystallisa- 
tion are greatly complicated and do not admit of any quan- 
titative deductions beg made. 

(b) The compound has no definite melting point, and decom- 
poses on melting.—In this case the diagram assumes the form 
shown in Fig. 5. 

As was said above, the compound does not melt to a 
homogeneous liquid, but at a given temperature decomposes 


10 CHEMICAL COMBINATION AMONG METALS. 


into a liquid of definite composition and a crystallime portion 
with a higher melting point, which in the case indicated in the 
figure is the component B. This process is expressed by the 
following equation :— 
A, B, 2 CB+([(n—c) B+ mJ], 
(crystals) (liquid) 

in which C indicates the number of molecules of B produced 
per molecule of A,, B,. 

The process of solidification corresponds to the case in 
which the compound can only exist m the presence of an 
excess of one of the components. The dotted line which is 
prolonged from ¢ indicates a region of metastable equilibria 
and the maximum g corresponds to the composition of the 
compound. From the diagram we may deduce the thermal 
phenomena which accompany the solidification of mixtures 
of varying composition. It is worth while noticing the 
changes which accompany the cooling of a melt of com- 
position A, B,. The solidification begins at f, at which 
temperature the pure component B separates. The sepa- 
ration of B continues until the temperature has fallen to 
that of the horizontal through c, below which the compound 
can exist without decomposition. Here the separation of B 
ceases and the separation of the compound begins with a 
thermometric arrest corresponding to the distance between 
h and the horizontal. This arrest does not indicate the 
formation of an eutectic, but of the compound. The ther- 
mometric arrest is proportional to the quantity of the com- 
pound which is formed for a given quantity of mixture. 

Tammann,! who has discussed particularly the phenomena 
of crystallisation which occur, in the type of system just 
described, states that thermal analysis can safely be applied 
only when the following conditions are satisfied. 

1. The reactions which occur in the melt before and after 
crystallisation must occur fast enough to keep pace with the 
process of crystallisation. 


1 Zeit. anorg. Chem., 45, 24 (1905). 


EQUILIBRIUM DIAGRAMS. 14 


2. The quantity which crystallises in unit time should 
depend solely on the quantity of heat yielded up by the 
crystallismg mass. 

The phenomena of crystallisation are still more compli- 
cated if the compound splits up into a definite melt and 
another compound of different composition. 




















: 6 
(‘Qe 
( 
S46. 
re 
tA (S \ 
i‘ 
= sin e af ae Ox GP 
a a ee NS an 
ae od os Ae ae 
( 
1€s e, 
1 } 
| | 
\ ' 
j ' 
} f 
: \ 
] 
: | : ' 
A (  AmBn | B 
Pic: 0; 


(c) 1. The compound is strongly dissociated vn the fused 
state.—A particular case which in many respects resembles 
the one just examined is that indicated in Fig. 6. The 
maximum ¢’ which indicates the compound does not exist 
in reality, being flattened out to c. But this temperature 
corresponds simply to that of the two points e and e’, which 
are the two eutectics—one between the component A and the 
compound, and the other between the component 6 and the 


12 CHEMICAL COMBINATION AMONG METALS. 


compound. The solidification of a mixture corresponding 
to the composition of A,, B, is accompanied by a trans- 
formation at ¢ where the compound separates. The solidifi- 
cation of the melts corresponding to the two eutectics takes 
place at the same temperature, but the arrests in these cases 
are indicated by e e, and e’ e’, respectively. 

The equilibrium diagram of the system magnesium- 
aluminium, in which Mg,Al, occurs as a compound, approxi- 
mates to this, but a perfect example -has not yet been 
encountered in binary intermetallic systems. Such types 
have, however, been noted in certain organic binary 
equilibria.? . 

2. A very interesting case is that of a compound which 
forms on melting two layers miscible with each other at a 
_ higher temperature. The diagram in this case is referable to 
the simplest type shown in Fig. 7. Applying to this diagram 
the reasoning developed in the preceding cases, its structure 
is perfectly clear. The eutectics between the compound 
and the components areeande’. Along the line ae the pure 
component B separates. The horizontal tract M N deserves 
special notice. During the fusion of the mixtures of com- 
positions between M and N, two liquid layers are formed, 
so that the compound under certain conditions can exist in 
equilibrium with the two components. Within the curve 
M k N the two liquids exist in a form similar to the well- 
known emulsions of the organic chemist ; but above this 
curve they mix, forming a homogeneous liquid. The mixture 
of composition k, which corresponds to the compound A,, B, 
in composition, shows a maximal arrest which, according to 
the considerations already put forward in preceding cases, 
is not to be attributed to the formation of an eutectic. 

The liquidus curve is ae M N e’ b. The quantities of 
liquid which crystallise at the temperatures t,, t,, and ft, 


1 Cf. R. Kreemann: Mon. f. Chem., 25, 1215 (1904) ; 29, 877 (1908) ; J. P. Wibaut 
Rec. P.-B., 32, 244 (1913). M. Giua, Ber., 47, 1718 (1914) ; Gazz. chim. ital., 45, I., 
339, IL., 348 (1915). 


EQUILIBRIUM DIAGRAMS. 13 


respectively from equal quantities of homogeneous melts are 
represented by ordinates in Tammann’s diagram.’ The 
sreatest quantity is given by the liquid which crystallises at 
t, at the composition of the compound, while the quantities 














{ 


| 
} 
| 
! 
! 





' 
| 
f 
{ 
t 
| 
| 
| 
| 
| 
{ 








> 

3 
= r 

~ 

° 


ae 
| 
| 
! | 
A | 
| 
J 
| 


= 


M 





Se ee —_— 





} 
J 
' 
| 
i 
} bs 
! 
] 
1 


| SS 


/ 


—— ow we +H 


) 








iii 





Fig. 7; 


which crystallise at t, and t; become nil for the compcsition of 
the compound. The duration of crystallisation also depends 
on the composition of the melt. There are thus three modes 
of determining composition. In this type the horizontal 
line M N may be supposed to culminate in k’. 


1 Zeit. anorg. Chem., 47, 296 (1905). 


14 CHEMICAL COMBINATION AMONG METALS. 


A sodium-zinc compound of the formula NaZn,, is of the 
type just described. 

Cuass III. The two components form solid solutions.—The 
diagrams which represent the curves of crystallisation of 
binary mixtures where solid solutions occur have been 
described and assembled into five types by Bakhuis Rooze- 
boom.! The five types of solidification have been divided 
into two groups according as they show partial or total 
miscibility. Although Roozeboom’s types taken singly do 
not include the case of the formation of definite compounds, 
yet they are of great interest because one can often verify the 
fact that compounds resulting from two components form 
mixed crystals between more or less wide limits. 

In the first group are comprised the types I, II and III, 
in which complete solubility exists between the two com- 
ponents in both the liquid and the solid states; in other 
words the fused components solidify forming a continuous 
series of mixed crystals. 

Types IV and V form the second group; in _ these, 

the components are only partially miscible in the solid 
_ state. 
Typs I. The two components form a continuous series of 
mixed crystals —They are completely miscible in the liquid 
and solid state, and form crystalline masses in which the 
components are not separate but homogeneously built up. 
The equilibrium curve assumes the form of Fig. 8. In this, 
the component A lowers the melting point of component B, 
while the latter raises the melting point of the former. 
No maximum, thérefore, occurs in this diagram. Three 
regions may be distinguished in the diagram: (1) that. of 
homogeneous liquid, (2) that lying between the liquidus 
curve and the solidus curve, and (3) that below the solidus 
curve in which homogeneous mixed crystals occur. 

A melt of composition a, if cooled, deposits mixed crystals 
of composition b, and thereby becomes richer in the com- 

1 Zeit. phys. Chem., 80, 385 (1899). 


EQUILIBRIUM DIAGRAMS. 15 


ponent A. Consequently, from the same melt there will 
separate along the curve b c a series of mixed crystals 
increasingly richerin A. The curve a¢ gives the composition 
of the corresponding melts. 

If it be desired to know the relative amount of mixed 











Ja 





e 
A Zz. i 

















B 


Fic. 8. 


crystals formed from a mixture of composition s at a 
temperature t,, it may be readily found from the diagram. 
If a line ef be drawn horizontally through t,, then e will 
indicate the composition of the fused lquid and f will 
indicate the composition of the mixed crystals. But the 
average composition will be represented by g, and therefore 


16 CHEMICAL COMBINATION AMONG METALS. 


weight of mixed crystals ge 
~ weight of fused mixture” gf, 

a relation which holds for melts and mixed crystals following 
the lines ah and bi respectively. In the vicinity of the line 
hv the residual liquid is almost nil and the alloy consists 
almost entirely of mixed crystals. 

Several alloys of gold, copper and iron belong to this type. 

Type Il. The fused mixtures deposit a continuous series of 












! 
| 
' 
| 
i 
' 
) 
! 
| 
! 


A iM Cc <i 


HIG: 9; 














mixed crystals : the curve passes through a maxvmum.—Lach 
component raises the melting point of the other,as is shown in 
Fig. 9. In this case the curves are quite simple. The 
liquidus curve is indicated by af ¢ b and the solidus curve 
byakck’'b. A mixture of composition M between a and ¢ 
(or between b and c) solidifies in the temperature interval f k. 
The composition of the mixed crystals, as in the preceding 
type, will differ from that of the liquid. The mixture of com- 
position c has, however, a definite solidification point, and to 
that extent resembles a simple substance. It is constituted of 


HQUILIBRIUM DIAGRAMS. Ly 


homogeneous crystals just as a chemical individual, and 
appears thus under microscopical examination. 

This type of crystallisation has been recognised in the 
binary system lead-thallium (see Chapter V). 

Types III. The fused mixtures deposit a continuous series of 
mixed crystals ; the curve passes through a minimum.—EKach 
of the components lowers the melting point of the other. 
The diagram is indicated in Fig. 10. The considerations 

















A ‘& B 
Fig. 10. 





put forward in the last case hold in an inverse sense for 
mixtures of this type. The alloys copper-manganese, 
copper-gold, nickel-manganese and various others belong 
to this type. 

Tyee LV. The solidification curve exhibits a transition pownt. 
—This type is shown in Fig. 11. As is seen, component A - 
lowers the melting pomt of component B, while the latter 
raises the melting point of the former. It has already been 
stated that in this type and the next mixed crystals are not 


formed in a continuous series. The two liquidus curves are 
O.M. 2 


18 CHEMICAL COMBINATION AMONG METALS. 


ac and bc; the solidus curves a d and b e intersect the 
horizontal through ¢ in d and e. At the temperature of the 
line c d e the melt of composition represented by ¢ is in 
equilibrium with two separate mixed crystals of composition 
represented by d and e respectively. At this point there is, 
of course, a discontinuity. In the solidification of a fused 
mixture 7, intermediate in composition between ¢ and d, 
mixed crystals of composition n, will separate at the point n. 











a : 
n nr 








N i 











PIG. 14, 


Below the point ¢ the mixed crystals which separate will lie 
along the curve d ng and be in equilibrium with melts lying 
along the line ¢ ng. 

Type V. The solidification curve exhibits an eutectic point. 
—KHach of the two metals lowers the melting point of the 
other (see Fig. 12). This type is similar to that described on 
p. 2. The liquidus curve is shown by a e b, the solidus 
curve by af gb. In the solidification of a mixture of com- 
position e, the liquid will be at that point in equilibrium 
with mixed crystals f and g. This solidification takes place 


EQUILIBRIUM DIAGRAMS. 19 


at aconstant temperature and causes a maximal thermo- 
metric arrest. 

It will, of course, be quite easy to trace the course of 
solidification of a mixture n: its behaviour will be exactly 


1 
fovea G4 
rR 














A we) 
Fia@, 12, 











similar to that of the mixture considered in Type I (see 
p. 14). . 
This type of solidification is fairly common in binary 
mixtures of metals, as in the alloys copper-gold, nickel-gold, 
aluminium-zinc, bismuth-lead, and many others. 


to 


ames 


CHAPTER IL. 


THERMAL ANALYSIS. 


Ir, in the study of equilibrium curves a maximum is 
found, it may be inferred with considerable probability that 
a compound has been formed whose composition is indicated 
by the position of the highest point of that branch of the 
curve in which the said compound occurs. It 1s frequently 
the case, however, that this criterion does not suffice to estab- 
lish the formation of such a compound, and it 1s only with the 
aid of thermal analysis, recently introduced by Tammann, 
that safe conclusions can be drawn. ‘Tammann’s method is 
based on the interpretation, not only of the first arrests 
noted in cooling curves (which serve to define the liquidus 
curve), but also of other arrests due to the solidification of 
eutectics or to polymorphic transformations within single 
phases. It is necessary to call attention to the importance 
of the magnitude of the arrest, which is of course propor- 
tional to the thermal change, in thermal analysis. Generally 
speaking, a maximum thermometric arrest corresponds to 
the formation of an eutectic alloy ; but this cannot always 
be inferred. If, for example, at the temperature of eutectic 
solidification, the separation of a phase occurs, the ordinary 
thermal changes may not take place and the eutectic arrest 
may thereby be masked. 

The results obtained by thermal analysis are not, then, 
of absolute value in determining the capacity of two sub- 
stances to form definite compounds with each other. In 
the first place, such capacity can only be determined by 
the thermal method over a range of temperature limited by 
the conditions of the experiment. There is also a second 
limitation: thermal analysis studies processes which take 


THERMAL ANALYSIS. 21 


place in heterogeneous systems and cannot take account of 
processes occurring in homogeneous liquids. In liquid mix- 
tures phenomena are noted concerned with the molecules, 
which act as crystallisation nuclei. Given the limitation of 
our knowledge and the theoretical and experimental diff- 
culties which hinder a complete elucidation of the subject, 
the thermal method is not always sufficient for the solution 
of a given problem. Recently, however, by the application 
of physico-chemical methods to the problems of equilibrium 
new cases have been brought to light and our knowledge has 
been extended. A classical example is given by the bismuth- 
thallium alloys. The investigations of this system by 
M. Chikashigé 1 had given evidence of the existence of a 
compound of the formula Bi;Tl,; but recent researches of 
Kurnakoff and his collaborators ? on the fusion curves and 
electrical conductivity have demonstrated the existence of a 
y phase which occurs between 55 per cent. and 64 per cent. 
(atomic) of bismuth. This phase exists perfectly inde- 
pendently, but cannot be fitted into any of Roozeboom’s 
types for solid solutions. Further, microscopic examination 
showed that it undoubtedly possessed the characteristics 
of a chemical compound. According to Kurnakoff, Chika- 
shigé’s contention that there exists a compound B6i,T'l, 
capable of forming solid solutions with excess of thallium or 
bismuth is not admissible, because the singular points noted 
do not correspond to the limits of the compound’s existence. 
We shall have occasion to return later to this case, which 
constitutes a clear case of a chemical individual which does 
not obey the law of definite proportions. 

The phenomena observed in the cooling of a liquid sub- 
stance are well known, as also the course of the cooling 
curve of two or three substances fused together ; the pheno- 
mena differ according to the degree of miscibility in the solid 
and liquid states. All these cases have been sufficiently 


1 Zeit. anorg. Chem., 51, 328 (1906). 
2 Jbid., 83, 200 (1913). 


92 CHEMICAL COMBINATION AMONG METALS. 


discussed. We prefer to confine ourselves particularly to 
the questions relating to the formation of chemical com- 
pounds. The forms of the principal curves have been 
already described (see Chapter I). As has been said, and as 
we shall repeat, the mutual behaviour of two substances is 
comprehensively and completely described by their equili- 
brium diagram. With changes in the concentration of two 
substances there are always definite thermal changes from 
which general ideas can be obtained as to the structure of the 
solid phase (see p. 20). As we have seen in the foregoing 
discussion on equilibria, the interpretation of diagrams 
where compounds occur is often rendered difficult by the 
appearance of new phases. 

Many compounds which have definite maxima are able 
to form solid solutions with one or both components and 
between varied limits. Generally, in the diagrams for metals, 
various phases appear which may render it impossible to 
interpret rationally the variations of thermal equilibrium. 
The diagrams representing systems in which compounds 
occur capable of forming solid solutions with the components 
are of great importance from the point of view of chemical 
theory. We shall speak of these in the section on chemical 
compounds of variable composition. 


CHAPTER III. 


THe NAtTuRE OF INTERMETALLIC CoMPOUNDS. 


The Concept of Chemical Combination and the Phase Rule. 


Tur fundamental principles of the Phase Rule and its 
varied applications in physical chemistry have already been 
expounded in numerous publications treating of metallo- 
graphy. This is not the place for even an outline of the 
subject and we shall therefore assume as well known the 
fundamentals of Gibbs’ theory of heterogeneous equilibria.! 

In dealing with intermetallic compounds, however, whose 
nature is not yet completely understood and about which 
considerable differences of opinion exist, it will be well to 
begin by elucidating a concept which has an important 
historical significance. 

In the development of the natural sciences, since the first 
realistic efforts of the Renaissance, certain general principles 
or fundamental concepts have formed the bases on which 
experimental science has been built up. To confine our- 
selves only to the matter which concerns us in the develop- 
ment of our subject, the concepts of element, simple sub- 
stance and chemical compound formed for some centuries 
the principal subject of chemical investigation, so that all 
the theories which have held and still hold in science seem 
intimately bound up with these concepts. 

iven in ancient times logical and scientific methods 
developed securely on the bases of fundamental concepts, 
although these may have been causes of error. Among these 
concepts, that of ‘‘ element ’’ has dominated the greatest 
philosophic minds from the most remote antiquity. 

“ The influence exerted by this doctrine of the elements,” 


1 Roozeboom: Heterogenen Gleichgewichte, Vols. I. and II. 


94 CHEMICAL COMBINATION AMONG METALS. 


says E. von Meyer,! writing of Aristotle and Empedocles, 
“together with its philosophic offshoots on all trends of 
thought was remarkable. All the scholasticism of the 
Middle Ages was grounded on this assumption, which became 
the fount of innumerable errors.’’ Nevertheless the logical 
basis of science has remained, as also the idea that matter in 
all its varied forms is derived from the elements.? 

For modern chemistry the most important property of 
chemical compounds is constancy of composition. But 
now, according to Kurnakoff the terms compound and 
indwidual have almost the same significance. 

It has fallen to W. J. Gibbs * to introduce a new funda- 
mental concept, namely, that of phases, 2.e., a system of 
equilibrium formed of homogeneous bodies separated from 
each other by surfaces. We must attribute an almost abso- 
lute individuality to this concept. By meang of it, inter- 
metallic compounds, as also many other complexes, organic 
and inorganic, which remained completely obscure on the 
basis of older principles, have received a rational explanation. 

It should also be mentioned that the concept of phase is 
much wider than that of chemical individual in the 
Daltonian or Berzelian sense, because by it is indicated not 
only bodies of constant composition but also the important 
class of solutions and homogeneous bodies of variable 
composition. 

According to the idea first expressed in 1897 by the 
technical chemist, Fr. Wald,’ a chemical individual repre- 

1K. von Meyer: History of Chemistry. | 

* Meyer also writes of the ancients: ‘‘ In the concept of chemical combination, also, 
we occasionally meet opinions diametrically opposed to those of to-day. In those 
days the formation of a substance from the interaction of other substances was con- 
sidered as the creation of a new substance and it was considered that an annihilation 
took place of the substances from which it was derived. In all directions the mind 
was the slave of theoretical speculations, without rigorous experimental proof. This 
lack appears clearly evident from the way in which the ancients viewed the numerous 
chemical phenomena with which they became acquainted either casually or empirically. 

% Zeit. anorg. Chem., 88, 109 (1914). 

4 Thermodynamic Studies, 1876—78. 


® Zeit. phys. Chem., 18, 337 (1895) ; 19, 607 (1886) ; 22, 253 ; 28,78 ; 24,315 (1897) ; 
25, 525; 26, 77 (1898); 28, 13 (1899). 


NATURE OF INTERMETALLIC COMPOUNDS. 25 


sents a phase which in a series of equilibrium changes 
possesses a notably constant composition. 

Kurnakoff,' holds that this definition gives anew aid 
to the recognition of a chemical compound. “ The pure 
naturalistic and logical conception of a phase here coincides 
with the mathematical conception of a determinate com- 
pound. The phase which exists independently would appear 
to have indwidual characters and show substantially the 
manifestations of the ideal complex of atoms which we call 
a compound. Many definite compounds have been discovered 
by means of their reactions or from the diagram of their 
properties ; but up to the present they have not been considered 
as chemical individuals. In order to be able to demonstrate 
their existence, 1t has been considered necessary to rsolate them 
in the form of single and vndependent phases.” 

The first task, therefore, in the investigation of compound 
systems is that of establishing the genetic relation among 
existing phases and of classifying the individuals. From 
this point of view the domain of chemistry comprehends the 
classification and study not only of compounds of constant 
composition, governed by the well-known principles of 
Proust, but also of solutions, till now considered as homo- 
geneous physical mixtures. Under the phase rule they 
come to be treated by the same logical method. 

As far back as 1907, R. Nasini”® had placed in clear relief 
the importance of indefinite combinations in physico- 
chemical research. He says,’ ‘‘ Another wmportant and 
fertile region of unlooked-for results is that of the study of 
physical mixtures, of complex combinations, of combina- 


1 Zeit. anorg. Chem., 88, 109 (1914). 

2 R. Nasini: La chimica-fisica, il suo passato, quello che é& e quello che si propone. 
Padua, 1907. 

3 Op. cit., p. 38. The same concept has been developed by Le Chatelier, who writes : 
** On account of the clearness which was given to chemistry by the concept of definite 
chemical compounds investigators have long occupied themselves especially with the 
study of these bodics. Compounds with variable composition, solid solutions and 
homogeneous liquids were on the contrary held of small account, although the 
importance and significance of these bodies in the study of natural phenomena are 
considerable.” Lecons sur le charbon, p. 385. Paris, 1908. 


296 CHEMICAL COMBINATION AMONG METALS. 


tions of indefinite composition, as Guldberg calls them and 
as Mendeléjeff called them before him. There vs no doubt 
that in the past chemistry has been too exclusively occupied 
—although to a large extent necessarily—with the simplest 
chemical species and has taken little notice of solutions or 
homogeneous mixtures, including solid solutions and_ the 
complex combinations which can exist in and be formed 
from them in various ways. Wherefore it may very 
reasonably be said that chemistry—even physical chemistry 
until a few years ago—was the science only of the most sumple 
and stable chemical species. Having regard to the isolated 
occurrence in nature of such species and thew laboratory 
origin, these are almost rarities and singular cases obtained 
and isolated with considerable trouble and artifice. Wald 
said, indeed, that chemistry only studied and made collection 
of rarities. Physical chemistry, in fact, finally turned its 
attention to homogeneous and heterogeneous physical mixtures, 
to the more complex combinations, those of indefinite com- 
position ; rt has vn other words turned to the study of materials 
which directly and actually present themselves and with which 
we find ourselves im contact without the preoccupation of 
attempting to isolate from them sumple chemical species.” 

Without wishing to discuss, for the moment, the value of 
the new concept of phases introduced into modern physico- 
chemical investigation, we will only say that it has been 
and is of indispensable value in the treatment of indeter- 
minate complexes as stated in the judgment of Nasini 
quoted above. 

In the following pages the problem of intermetallic 


compounds of variable composition will be more particularly 
discussed. 


Intermetallic Combinations of Variable Composition. 


Before discussing this important aspect of equilibrium 
diagrams for binary systems and making any observations of 
a general character, it may be well to mention that in our 


NATURE OF INTERMETALLIC COMPOUNDS. 27 


treatment of the subject we include all cases in which the 
compound or compounds formed can give solid solutions 
with one or both components over more or less wide ranges 
of concentration. 

The types described in Chapter I relating to the existence, 
as shown by the equilibrium diagram, of definite compounds, 
fall according to the extent of the series of solid solutions into 
the different types in Roozeboom’s classification as outlined 
onp. 14. Asin the preceding pages, we shall here give some 























b 
e 
ea 
A Hae Bix RB 
BIG. V3. 


indications on the possible interpretation of equilibrium 
diagrams. The following types will be discussed :— 

I. The compound is completely soluble wm its components 
even in the solid state. 

II. The compound, which has a definite melting pont, forms 
solid solutions with excess of the components. 

III. The compound, though forming solid solutions with its 
components, dissociates on fusion. 

Typr J.—In this type may be grouped the systems whose 
diagrams are indicated by Figs. 13, 14, and 15 respectively, 
according as the melting point of the compound lies between, 


98 CHEMICAL COMBINATION AMONG METALS. 


below or above the melting points of its components. In the 
three diagrams the alloys of composition 4,, B, correspond- 



































ee , 
C 
Am\ Br of 
Fig. 14. 
¢ 
O b 
A 7 Audion B 
Fie. 15. 


ing to definite compounds solidify homogeneously at the 
point c. For alloys lying between a and c or b and ¢ the 


solidification proceeds as in Roozeboom’s first type described 
on p. 14. © 


NATURE OF INTERMETALLIC COMPOUNDS. 29 


Type I[.—This is indicated in Fig. 16 and is equivalent 
to the fusion in juxtaposition of two systems, each belonging 
to Roozeboom’s fifth type. 

The considerations developed concerning this type are 
sufficient to explain all the processes of solidification of 




















jg Ao B 


Fie. 16. 





fused mixtures whose compositions vary from A to B. The 
liquidus curve is represented by the line a e x e’ b and the 
solidus curve by the line af g af’ g’ b. This type is very 
common in metallic alloys which form compounds with 
well-marked melting points. The thermal results have 
often been confirmed by micrographic analysis. The alloys 
corresponding to the two eutectics e and e’ are distinguished 


80 CHEMICAL COMBINATION AMONG METALS. 


by a very characteristic stratified structure; in the region 
where solid solutions occur, the structure is quite homo- 
geneous. It may be seen, then, from the diagram, how the 
composition of the solid phase of a compound can vary 
between limits. As has already been said, solid solutions 
frequently occur in the formation of compounds, so that 
generally, the concentration of the liquid or solid phase of a 
compound is variable, and in such cases the concentration 























A | 5 Am Bir és 


FIG. 27; 





corresponding to the maximum of the diagram cannot | 
always serve as a criterion to establish the true composition 
of the compound. In the later part of the work we shall 
frequently have occasion to return to this problem, which is 
becoming of increasing importance. The study of the 
physical properties of alloys (see Chapter IV) is of great 
service in the interpretation of those problems for which 
the thermal method has proved inadequate. 

Type III.—The diagram is shown in Fig.17. The liquidus 
curve 1s given by the line a e ¢ b while the solidus curve is 


NATURE OF INTERMETALLIC COMPOUNDS. 81 


given by af ghh' b. From the diagram the processes of 
solidification along a e, ¢ e and ¢ b become quite clear. The 
alloys from ¢ to h’ in which the compound 4,, B, is formed 
have very complicated crystallisation processes, because 
the compound does not actually exist as such even in the 
solid state, being spht up into conjugate solid solutions. 
The systems silver-antimony, silver-tin and various others 
belong to this type. 

The recent developments of the thermal method and of 
physical methods in general, which are of such service in the 
investigations of modern metallography have led various 
investigators to give a scientific value to the idea of the 
existence of compounds of variable composition or indefi- 
nite compounds, an idea championed by Berthollet in his 
classical dispute with Proust on the limits of chemical 
combination. Berthollet foresaw clearly this unknown 
realm of science? and asserted that “ compounds which 
are formed with slight contraction can be found in all pro- 
portions and their composition is only lumited by their 
capacity for saturation. Thus, alloys, glasses and minerals 
are formed in diverse proportions im which occasional gaps 
occur.” 

Avogadro also, who was an admirer of Berthollet, quickly 
recognised the importance of such indeterminate compounds 
in chemical theory. (Guareschi in his work on Avogadro ? 
has given evidence of the breadth of view of the great 


1 C. L. Berthollet : Hssai de Statique Chimique, I., 373 (1803). 

2 I. Guareschi: Opere scelte dt Amedeo Avogadro. Turin, 1911. In the critical and 
historical discourse introductory to the literature of Avogadro’s works, Guareschi 
writes (p. cix.), ““ Avogadro was disposed to admit Berthollet’s ideas on chemical com- 
bination in indefinite proportions. Naturally, he believed in the definite 
proportions in which gases combined; yet he believed that in certain cases the 
ideas of Proust and Dalton could be reconciled with those of Berthollet. At the 
end of his classical memoir (J. de Phys., 1811, LX XIII., pp. 58—76) he writes, ‘ If we 
consider the approach of molecules in solid or liquid bodies, when the spaces 
between the integrating molecules are not of the same order as those between the 
elementary molecules, combinations may occur in complicated proportions, but these 
combinations are of a different nature ; this idea may serve to reconcile the ideas of 
Berthollet with the theory of fixed proportions.’ These ideas are entirely modern and 
the work on colloids has rendered this kind of combination very probable.” 


82 CHEMICAL COMBINATION AMONG METALS. 


Piedmontese physicist and chemist. Guldberg,! in 1870, 
recognised the importance of mdeterminate compounds. 
They have recently received fresh ight from the labours of 
Fr. Wald, already noted. ‘The treatment of the matter by 
this ardent investigator is certainly not the most adapted to 
throw into relief the importance of the subject of indeter- 
minate compounds because ‘he has attempted to extend to © 
all branches of chemistry particular concepts which have 
only a limited application, seeking, in fact, to diminish the 
importance of the atomic and molecular theory—a theory 
which we may say was born in Italy, first of Avogadro and 
then of Canizzaro. 

R. Nasini? has amply dealt with this argument in a 
notable contribution to which we shall return later, as it has 
no direct bearing on the present theme. 

It is of importance to note that the fundamental principles 
of chemistry are always essential in the study of compounds 
of constant composition, but that, naturally, they cannot 
serve as a guide to the investigation of the indeterminate 
compounds, whose existence and importance we have indi- 
cated. In order to obtain knowledge of this still obscure 
subject, the principles of the Phase Rule, together with 
some concepts developed by Fr. Wald, may guide us and 
oive us fresh light. We may record in this connection the 
contribution of Kurnakoff* on the interpretation of equi- 
libria among different phases. 

In an equilibrium diagram in which a compound capable 
of forming solid solutions with its components appears, there 
is a characteristic which should be noted at once. When 
the electrical conductivity of these solid solutions is studied, 
the isotherm shows two branches which intersect in a point 
corresponding to the maximum on the thermal diagram 
(see Chapter IV). 


1 Guldberg: Beitrag zur Theorie der unbestimmten chemischen Verbindungen 
Ostwald’s Klassiker, n. 139. 

* Gazz. Chim. Ital., 36, 1., 540 (1906) ; ibid., 37, I1., 137 (1907). 

3 Zeit. anorg. Chem., 83, 500 (1913). 


NATURE OF INTERMETALLIC COMPOUNDS. 83 - 


The meeting point of two single branches on curves 
of physical properties is called by Kurnakoff a singular 
pont and characterises the composition of a definite com- 
pound. ‘This conception, taken from the theory of algebraic 
curves, is very happy on account of the light it sheds on the 
question of equilibria among diverse phases. These singular 
points, which are necessary criteria for the determination of 
compounds in solid or liquid homogeneous media, have been 
called by Kurnakoff Daltonian points, since they illus- 
trate Dalton’s law of multiple proportions. 

By means of this conception the composition of a definite 
compound may be indicated. Kurnakoff says,! “Jt ts not 
the composition of the phase, which is generally variable, 
but the composition at the singular or Daltonian point which 
vs characteristic on the diagrams showing the properties of a 
determinate compound. ... A chemical indwidual repre- 
sents a phase which shows singular or Daltonian points on 
the curves of rts properties. The composition which corre- 
sponds to these pornts rs the same vn all changes of the factors 
of equilibrium of the system.” 

This definition is not valid for a compound of variable 
composition, because singular points are lacking on the 
diagrams of its properties. We shall, therefore, define an 
indeterminate compound? in the following manner :— 

“A chemical individual of variable composition represents 
a phase which does not show singular or Daltonvan pornts on 
the curves of vts properties.” 

In the description of equilibrium diagrams we shall 
frequently note the existence of intermetallic compounds of 
variable composition. In the systems thallum-bismuth 
and mercury-thallium, such compounds appear; they are 
more common than is generally believed, for among them may 
be placed those independent solid phases, indicated in the 


1 Zeit. anorg. Chem., 88, 109 (1914). 

2 Kurnakoff proposed to term such compounds Berthollides ; this denomination, 
however much an act of remembrance of the great chemist, should not be introduced 
into use, strictly scientific terms being preferable, 

C.M. 3 


84 CHEMICAL COMBINATION AMONG METALS. 


description of binary systems by Greek letters. Such are 
the phases 8, y and 6 of the ferro-silicon alloys and those of 
copper and silver with tin, cadmium and zine (see Chapter V). 


Intermetallic Compounds and the Theory of Valency 
(TamMANN’S Rutgss). 


The description of the behaviour of the elements, which 
forms the main theme of general chemistry, presents to-day 
three gaps which will in time be filled as a result of the 
efforts made to extend our knowledge. ‘These are in- 
organic complexes, intermetallic compounds, and organic 
additive molecular compounds. The co-ordination numbers 
of Werner, illustrated by numerous and careful experi- 
mental investigations, have shed considerable light on the 
inorganic compounds, so that it may be safely affirmed 
that they constitute the most enterprising attempt at 
systematisation since the periodic law of Mendeléjeff and 
Lothar Meyer. The same cannot be said of intermetallic 
compounds and the molecular compounds of organic — 
chemistry. The ordinary ideas of valency are insufficient in 
most cases. It is known also that some intermetallic com- 
pounds do not conform to the law of definite proportions, 
thus bringing to life the celebrated dispute between Proust 
and Berthollet on the limits of chemical combination 
(compare p. 31). 

_As Tammann remarks,! the theory of valency has given 
abundant fruit in two great chemical groups, namely, the 
carbon compounds and the inorganic salts. The latter are, 
above all, governed by very simple rules in which the 
character of the element has a relative importance. Regard- 
ing, in place of these, the intermetallic compounds, it is seen 
at once that only a very small minority can be explained on 
the basis of the known saline valencies of their constituent 
elements. Tammann may well conclude, therefore, that 


1 Cf. Lehrbuch der Metallographie, Chemie und Physik der Metalle und thre Legierungen, 
p. 229. Leipzig, 1914. 


NATURE OF INTERMETALLIC COMPOUNDS. 35 


“Judging from the material at our disposition relating to 
the binary compounds, a can be maintained that their 
formule, where these compounds are not saline in character, 
are not generally determined by saline valencies.”’ 

Confining ourselves only to a few examples, we will con- 
sider two groups of metallic compounds—the amalgams of 
the alkali metals and the compounds of magnesium and 
thalhum. Lithium, potassium sodium and cesium form 
with mercury a complete series of compounds of the type 
R Hg, (where R = alkali metal).” Rubidium forms with 
mercury the compound RbHg, alone. But besides the series 
mentioned, which is the most stable, we find the following 
compounds :— 


Li, Hg KHe- Na,Hg Cs,Hg 
Li,Hg KHg, Na, Hg, CsHg 
Lig KHg, Na,Hg, CsHg, 
LiHg, K, Hg, NaHg CsHg, 
Lig; KHg, ‘ = ane 8 noes 
alles SILAS 10 
NaHg, 


The behaviour of magnesium is noteworthy because it 
‘gives rise to compounds with other metals showing quite 
distinct melting points. With thallium, magnesium forms 
the following compounds :— 


Mg, Tl,, Mg,Tl and Mg,T'l,. 


The compounds formed by mercury with the alkali metals, 
all more or less stable, are differentiated by their saline 
character. Mercury, indeed, forms compounds of the type 
R Hg, but the most stable compounds are those of the 
type R Hg., where the saline valency of the alkali metal 
cannot hold. 

The same considerations may be applied to the compounds 
which thallium forms with magnesium. It is, perhaps 
unnecessary to mention that thallium has a double character 
in its alloys. In its behaviour with sodium and potassium it 


1 Tammann, op. cit., p. 232. 
2 Cf. N.S. Kurnakoff and G. J. Zukovsky, Zeit. anorg. Chem., 52, 416 (1907). 


3—2 


86 CHEMICAL COMBINATION AMONG METALS. 


is related to mercury, cadmium, lead and the heavy metals, 
forming the so-called thallides similar to alkaline mercurides, 
cadmides and plumbides, but on the other hand it has the 
property of forming solid solutions with heavy metals such 
as bismuth, lead, tin, cadmium and mercury. 

The foregoing considerations become clear on examining 
the individual character of metals in their reciprocal com- 
pounds. | 

There frequently exists a certain analogy between the 
compounds which metals of a sub-group of the periodic 
system form with another metal, as, for example, in the 
following series :—- 

CuMg, AgMg AgMs, Cu,Zn, Cu,Cd, AgCd, 
AuMg, AuMg AuMg, Au,Zn, Ag oCd, AuCd, 


Cu,Al CuAl -CuAl, Ag,Al Cu,Sn  Cu,Sb 
AgsAl AuAl AuAl, AusAl <Au,Sn Ag,Sb 


PbPt Sb,Pt Cu,Zn, Ag.Zn, AgZn AuSn, 
PbPd Sb,Pb  Cu,Cd, Ag,Cd, AgCd AuPb, 


Mg,Sn Mg,Sb, TI,Sb  SnNi,  Sb,Zn, SbZn 
Mg,Pb Mg,Bi, TI,Bi  SnPt,  Sb,Cd, SbCd 

SbNi NiSb PtSn 

SbPd NiBi PtPb 

But, as ‘'ammann observes,” the analogy extends only to 
any two members of the copper sub-group and makes an 
exception of the third member. 

In chemical combinations the metals, apart from the 
nature of their saline valency, often unite atom with atom, 
which shows a certain simplicity in the bonds of atomic 
forces. The fact noted by Rausch and Traubenberg ? and 
mentioned in this connection by Tammann himself that in 
electrical discharges metallic atoms bear equal quantities of 
electricity, leads us to regard intermetallic combination as 
having an electrical nature; this case would thus be 
governed by Faraday’s second law of electrolysis.4 


* Cf. Kurnakoff and Pushin: Zeit. anorg. Chem., 52, 430 (1907). 
2 LOG; cit; 

3 Phys. Zeit., 1912, p. 415. 

* Cf. H.C. Jones; Elements of Physical Chemistry, pp. 352, 362. 


NATURE OF INTERMETALLIC COMPOUNDS. 387 


From the relations among the members of the same 
natural group of the Periodic System and among the 
members of different groups, Tammann?! has enunciated 
two rules which may be thus stated :— 

1. The elements of a sub-group of the Periodic System do not 
form compounds with one another. 

2. An element either forms compounds with all the members 
of a sub-group or with none of them. 

An exception to the first rule occurs in the combination of 
bromine and iodine and also in the iron group. But it must 
be mentioned that this rule has not a general character, as 
indeed frequently happens in the relations based on the 
Periodic System. If, for example, we enunciate the rule as 
follows: The similar elements of a natural growp of the 
Periodic System do not combine with one another, several 
exceptions at once appear. Kurnakoff has found (see 
Chapter V) that in the first group sodium combines with 
potassium and may possibly combine with other similar 
members of that group. Here our knowledge is indeed 
faulty. In the second group, magnesium combines with 
zinc, and cadmium with mercury, forming compounds with 
distinct melting points. 

The exceptions to the second rule are more numerous. 
For example, lead dees not combine with copper, nor does 
it mix in the liquid state; on the other hand it com- 
bines with gold forming two definite compounds; it mixes 
readily with silver, but without the formation of a com- 
pound—at any rate within the limits of thermal analysis. 
Thallium combines with mercury, forming a compound of 
variable composition, but does not combine with zine or 
cadmium. 

As we have already said, in order to explain the forma- 
tion of intermetallic compounds it is not possible to make 
use of the common conceptions of valency and chemical 
affinity acting between atom and atom. As it is generally 

1 Zeit. anorg. Chem., 49, 113 (1906) ; 55, 289 (1906). 


88 CHEMICAL COMBINATION AMONG METALS. 


necessary in the consideration of molecular compounds to 
admit the existence of inter-molecular forces, so for inter- 
metallic compounds analogous forces must be postulated, 
which may be related to the electrical nature of the atoms 
themselves. 

The idea of polar force is not new, since both Berzelius 
-and Mendeléjeff make use of it. It has been largely applied 
by R. Abegg! in the interpretation of variable valency. 
Nernst? also makes a clear distinction between polar 
and unitary forces. Polar forces depend on the special 
affinity of the elements for electrons, while wnitary forces 
lack this character. | 

According to Abegg, the valency of an element depends on 
the nature of the other elements with which it combines. 
Klements of distinct series in the Periodic System are hetero- 
polar, while neighbouring elements are homopolar. The 
greater number of intermetallic compounds result from 
unitary forces and only in comparatively few cases are hetero- 
polar compounds formed. In nature, among the few inter- 
metallic compounds the existence. of heteropolar types has 
been noted (see Chapter IV), and this fact may prove to be > 
useful in elucidating the capacity for chemical combination - 
among metals. 

Abege’s theory of valency is of considerable service 
in the interpretation of molecular complexes. In the 
contributions mentioned above, a sharp distinction has 
been made between the normal valency of an element 
and its counter valency. Assuming on the principles of 
the Periodic System that the sum of the valencies of an 
element towards oxygen and hydrogen is equal to 8, 
Abegg has given the following conspectus of the valencies 
of the elements comprising the different groups of the 
Periodic System. In this classification the relation of 
valencies is as follows :— 


1 Zeit. anorg. Chem., 39, 330 (1904) ; 50, 309 (1906). 
* Theor. Chem., p. 406, 6th ed,, 1909. 


NATURE OF INTERMETALLIC COMPOUNDS. 39 
































Groups. 
Vali ncies. : 
I | Il. | It IV W: Vin Vi 
Normal valencies .| + 1 | 2 3|,+4]—-3/] —-2|—-1 
Counter valencies Ke 7T)| (— 6) (- z| +5) +6 |+7 
| 





Staigmtller ' arranged all the elements of the Periodic 
System according to their electrical character ; the elements 
chemically analogous are near to each other, while the 
elements showing great affinity are remote from each other. 
The arrangement is as follows :— 


H He| Li Be|B C hs ieee 0 ae 
Ne| Na Mg Al| Si PS. Ol 
A |K Ca Sc Ti V Gr Mn Fe Ni Co Cu Zn Ga Ge \ AsSe Br 


Kr| Rb St Y Zr Nb Mo Ru Rh Pd Ag Cd In Sn SbX\Te I 
X |Cs Ba La Ce Nd Pr 


Vbe > fae Ww Os Ze Pt Aw He DT) Pb. Bi 
Ra Th U 








It will be seen that the alloy-forming elements are in the 
central part of the system, while the extreme members are 
of heteropolar character to each other and form compounds 
of a saline nature. 

Apart from the property of combination among metals, 
another character of great importance is their capacity for 
forming solid solutions. We have already touched on this 
point in the description of equilibrium diagrams. For 
further information we refer the reader to the celebrated 


monograph by G. Bruni: Feste Losungen und Isomorphismus, 
Leipzig, 1908. 


The Degree of Dissociation of Intermetallic Compounds. 


From the study of the equilibrium diagrams of alloys 
which form compounds with definite melting points it 


1 Zeit. phys. Chem., 39, 245 (1902). 


40 CHEMICAL COMBINATION AMONG METALS. 


appears that the position of the maximum which corresponds 
to a given compound rarely varies in a uniform manner. 
This fact is certainly related to the nature of component - 
metals or to their capacity for combination. We have 
mentioned the rules of Tammann which deal with this 
capacity for combination on the basis of the position which 
the individual metals occupy in the Periodic System. But 
as in related series of intermetallic compounds it 1s 
unusual to meet regularity in composition, so also in equill- 
brium diagrams the region of existence of the new phase- 
compound is variable. The position of the maximum point of 
a compound is, in fact,in close relation to its degree of dis- 
sociation. When from the diagram there appears a definite 
region of existence of a compound with a distinct maximum, 
it cannot always be concluded that the corresponding com- 
pound can exist as an independent phase, solid or liquid, at 
that temperature and concentration. Almost all the inter- 
metallic compounds are more or less dissociated in the fused 
state. A knowledge of the degree of dissociation is, there- 
fore, of great importance for the subject under discussion, 
since it is a characteristic property of every intermetallic 
compound and is, therefore, only definable under determinate 
conditions. Dissociation in molecular addition compounds 
can vary between wide limits, but we know very little as yet 
of the subject and this aspect of intermetallic compounds 
remains very obscure. The present work constitutes the 
first attempt to inquire into this important problem. 

How can the degree of dissociation of an intermetallic 
compound be determined ? Here again physical chemistry 
can give important help. It is known that the melting point. 
or freezing point of any compound, even if more or less 
dissociated, remains constant if the concentration of the 
components does not vary; changes of pressure under 
ordinary conditions have a negligible effect on the melting 
point of a substance. We can, then, profit by this experi- 
mental fact in the solution of our problem. It is a case, in 


NATURE OF INTERMETALLIC COMPOUNDS. 41 


fact, for the application of the cryoscopic method to the 
determination of the degree of dissociation of a compound. 

The lowering of the freezing point of water by an electro- 
lyte is always greater than that produced by a non-electro- 
lyte of equal molecular concentration. This fact, as is well 
known, gives a quantitative basis to Arrhenius’ ionic theory 
—an aspect lacking in the earlier theories of Grotthus, 
Clausius and Bartoli. 

If a molecule is dissociated into two ions the lowering of 
the freezing point of water is double that which it would be 
if the molecule were not dissociated ; it is n times greater if 
the molecule dissociates into n ions. Arrhenius used this 
fact to determine, by the cryoscopic method, Van’t Hoff’s 
constant, 7, introduced by him in his wide deductions from 
the laws of osmotic pressure. 

The degree of dissociation a for binary electrolytes is 
given by the equation— 

a=1—1 
[v is the number by which the expected depression of the 
freezing point must be multiplied in order to give the actual 
depression—in other words the number of ions formed by 
dissociation, per molecule of the electrolyte] and it is known 


t : 
that += 1:85 where ¢ is the observed molecular lowering 


and 1°85 the lowering of the freezing point by 1 gram mole- 
cule of a non-dissociated compound dissolved in a litre of 
water. 

For ternary electrolytes— 





1—I1 
a oe, y} “sy 
and in general for a substance dissociated into n ions— 
1—1 
a= ———_—- 
n —1 


This law holds for aqueous solutions, and if it could be 
extended to intermetallic compounds it would be at once 


42 CHEMICAL COMBINATION AMONG METALS. 


possible to determine the degree of dissociation a. Of 
necessity, intermetallic compounds cannot be dissociated 
into ions, but the atoms themselves into which the com- 
pounds are split act in the same way. : 

Adding to a given intermetallic compound a third metal 
capable of dissolving in it, but not forming solid solutions or 
combining with either of the components of the compound, 
there will be a lowering of the solidification point. This will 
be proportional to the amount of metal as long as the com- 
pound is not completely dissociated. If the compound is dis- 
sociated, then the point of solidification will be influenced 
not only by the added metal but also by the components 
into which it is dissociated, so that it will show a depression 
greater than that calculated by Van’t Hoff’s formula— 

02 T° 
gone 
in which Q is the latent heat of fusion and T' the absolute 
temperature. This formula, at least for low concentrations, 
permits the calculation of the lowering of the solidification 
point produced by the addition of a metal to the compound. 
Such a method allows us to obtain unexpected conclusions 
as to the nature of intermetallic compounds ; it has only been 
applied so far to a few organic addition compounds.! 

If a given compound AB breaks up in the liquid state 
into its components A and B, equilibrium exists when 

£1 tg = K [100 — (x, + 2,)] 
where 21, Zy, are the concentrations of A and B respectively 
and {100 — (x, + x,)| the concentration of the undissociated 
portion of AB. 

If, for example, the compound is dissociated to the extent 
of 10 per cent. into its components so that x = 7, = x, = 10 
and 100 — « = 90, then the constant K at the temperature 
of fusion is— 





100 
O° = bon 8 ht 


1 Cf. R. Kremann: Monatshefte f. Chem., 25, 1215 (1904). 


NATURE OF INTERMETALLIC COMPOUNDS. 43 


In this case in place of 100 moles we have 90 moles 
acting as solvent ; the 20 moles of products of dissociation 
cause a lowering of the melting point. The melting 
point, calculating the lowering per 100 moles, is lowered 


20+ 100 
110 


below what it would be if the compound were not dissociated. 


A 











Am a By 


Fig. 18. 











This factor must, therefore, be added to the value of A 
which is obtained for the addition of the metal to the 
compound AB, and which, according to hypothesis, behaves 
normally in the fused solvent. 

Kremann, in the paper cited, has calculated the lowering 
of the melting point of a pure compound from theoretical 
and practical considerations with regard to the position of 
the maximum corresponding to the given compound. In 
Fig. 18 is shown the solidification curve of two components 
A and B which give rise to the formation of a compound 


44 CHEMICAL COMBINATION AMONG METALS. 


A,, B, which melts at a temperature corresponding to the 
point e. The compound 4,, B, is formed along the branch 
of the curve c ec’ and shows a flattened maximum since it 
dissociates on fusion. If it melted without dissociation, 
the maximum would be higher, probably at e’, obtaimed by 
the intersection of the tangents drawn through the eutectic 
points cc’. The triangular region ¢ ec’ e’ is purely hypo- 
thetical and does not exist in reality. 

Almost all intermetallic compounds have more or less 
flattened maxima ; only certain compounds of magnesium 
and antimony are formed without a high degree of 
- dissociation. | 

Kremann’s calculated results are given in the following 
table. In the first column is shown the degree of dissocia- 
tion of a given compound, the second column x gives the 


| | 
| | 


a | ©& y 5 





Be oh oe ole ee 








| 
| 
| 
| 


bo 
(Sh 








5 | 0-2632 | 0 9-52 | 2 8-333} 0| 25-00 | 40-00 {11-1 
2 9-68 | iGo 22757 S007 hist 
6 10-55 | }12) 20-45 | 39-92 |1)-1 | 
12 13-81 }20 |} 17:99 | 40-56 |11-3 || 
20 18-51 |35| 14-43 | 42-74 |11-9 | 


| 
| |50 | 11-87 | 
|30 | 12-86 | 0| 30-00 | | 
LO Te Ot | | 6} 27-65 | 45-88 |12-7 | 
| 112 | 25-52 | 

| 

| 


eo 

or 
Nae ek Stier, ar, Ee Pee tee rk 
Oo ord OOe oS 
TITIONWNWASRP SO 

bo 

oO 

GO 

~J 


6 

i 

0 

8 

1 

9) 

4 

0 

Ly 

4 | 35| 19-17 | 
2 | 50} 16-37 | 
-9 || 35] 18-85 | 0; 35°00 | 51-85 {14-4 | 
2 | 6| 32-73 | 51-53 {14:3 | 
2 

2 

D 

0 

2 

6 

2 

2 

3 

6 


15 2-647 | 0/ 15-00 | 26-09 
12} 30-64 | 51-30 /14-3 





20| 28-13 | 
(35) 24-16 — 
| '50} 20-98 | 53-59 |14-9 
|50/50-00 0 50-00 | 








| 6) 48-05 | 66-30 {18-4 | 
/12| 46-13 | 65-97 [18-3 | 


20 5-000 | 0 20-00 | 33-33 
| 20 43-90 


lor) 
ah 
nS 
CO 
— 
- 
bo 


135! 40-00 | 65-72 |18-3 
(50 | 36:00 66-03 |18-3 






































NATURE OF INTERMETALLIC COMPOUNDS. 45 


equilibrium constant, a gives the number of moles of one 
component added per 100 moles of compound, « the number 
of moles of the other component after the change of equil- 
brium, y the number of moles lowering the melting point, 
calculated per 100 moles total, and 6 the depression of the 
melting point calculated from the preceding data on the 
assumption that a change of one mole causes a variation in 
the melting point of -278°. 


EXPERIMENTAL. 


It was desired to determine experimentally the degree of 
dissociation of the compound formed between bismuth and 
thallium (see Chapter V), a compound which, according to 
Chikashigé, has the formula Bi;Tl,, while according to 
Kurnakoff, it belongs to the class of compounds of variable 
composition. The case presents, therefore, a double interest 
because, if it were possible to demonstrate experimentally 
that this compound is more or less dissociated, the methods 
used by Kurnakoff to affirm the absence of singular points 
in the equilibrium curve corresponding to the range of 
existence of the compound may have a relative value 
applied to the casein point. It was, however, assumed that 
the compound Bi;Tl, exists. It was prepared by melting 
together in a Jena glass tube 62:955 om. of bismuth and 
37:045 gm. of thallium. The fusion was made in an atmo- 
sphere of hydrogen, because the resulting compound, as well 
as the components, change quickly in contact with air. The 
melting point was found to be 211-1°. 

‘To measure the degree of dissociation of this compound, 
tin was selected, a metal which does not combine with 
_ bismuth or thallium, as various workers have shown, and 
as was verified in the experimental part of this work. If 
in fact it entered into combination with bismuth or thallium 
the melting point of the compound would not be lowered 
_by the addition of tin. ‘Tin forms, it is true, solid solutions 
with bismuth and thallium,-but only to a limited degree. 


46 CHEMICAL COMBINATION AMONG METALS. 


The form of the curve for bismuth-thallium shows that 
between the limits of validity of the cryoscopic method 
this capacity should not exert any influence. We record 
on this point the investigations of Heycock and Neville! on 
the determination of the molecular weight of different 
metals (including thallium and bismuth) using tin as a 
solvent. 

The determination of the lowering of the melting point 
of the thalium-bismuth compound was made in a current 
of hydrogen; the thermometer, divided in tenths of a 
degree, had been standardised at the Charlottenburg 
Reichsanstalt (Berlin). For these determinations it is 
sufficiently accurate to work to one-tenth of a degree.? 

The whole apparatus consisting of the tube containing the 
substance together with the thermometer, the electrically- 
driven shaker and the tube leading the hydrogen from an 
ordinary Kipp, was maintained in a metal bath (Rose alloy) 
large enough to ensure a constant and not too rapid lowering 
of temperature. The results obtained are shown in the 
following table :— 





























Weight of thalli- 
~ jum-bismuth | Weight of tin, Tin, A A 
compound in grams. per cent. Found. Calculated. 
grams. 
33°0549 0) () — 50-39 
e 0-2314 O-7 o| » 
3 0-9579 2-89 127-34 ot 
S 15170 4-58 158 ee 
3°5650 10-78 145-7 5 
L 
| 











It is seen at once how the molecular lowering varies with 
the addition of tin from a minimum to a maximum value 
which remains nearly constant. We shall discuss this 
behaviour later. 

1 J. C. S., 55, 666 (1889) ; 57, 376 (1890). 


2 Tammann in his classical researches used a thermometer divided in tenths of a 
degree. Cf. Zeit. phys. Chem., 3, 441 (1889). 


NATURE OF INTERMETALLIC COMPOUNDS. 47 


The molecular lowering was calculated by Van’t Hoff’s 
formula. For this it was necessary to know the latent heat 
of fusion of the compound, and this was obtained approxi- 
mately by the method of G. Tammann?! and W. Plato? by 
examination of the curve of cooling. A mean of five deter- 
minations gave 93 cal. 

Up to a concentration of about 1 per cent. tin, the com- 
pound thallium-bismuth shows an inappreciable dissociation 
because the molecular lowermgs calculated and observed 
are particularly concordant. With the increase in the 
content of tin the compound is more and more dissociated, 
so that at a concentration of 4:58 per cent. of tin the 
observed value is triple the calculated value—an unforeseen 
result. 

In the application of the cryoscopic method to the 
determination of the degree of dissociation of an inter- 
metallic compound it was necessary to assume that the 
addition of an external substance did not influence in any 
way the dissociation of the compound, and such an hypo- 
thesis was all the more plausible since the dissociation in the 
case in question was not ionic but atomic. The results 
obtained, however, render this hypothesis untenable since, 
even at small concentrations, an external substance such as 
tin can influence notably the dissociation of an intermetallic 
compound. 

The fact that the compound TIBi, corresponding to the y 
phase of the system studied by Kurnakoff, shows practically 
no dissociation renders more clear the deductions of this 
intrepid investigator with reference to the existence of 
intermetallic compounds of variable composition. 

The compound thallium-bismuth alters rapidly in air; by 
the addition of tin it becomes very stable, so that with about 
10 per cent. of tin it retains its metallic lustre for a long 
period. 


1 Zeit. anorg. Chem., 43, 218 (1905). Cf. also Tammann, op. cit,, p. 31. 
2 Zeit. phys. Chem., 55, 721 (1906). 


48 CHEMICAL COMBINATION AMONG METALS. 


Existence of Intermetallic Compounds in the Vapour 
state. 


Our information as to the vapour tension of intermetallic 
compounds is not very extensive. H.v. Wartenberg* has 
recently published an interesting investigation in which 
the problem is given a theoretical basis. 

Experimentally the subject presents many difficulties. 
On the volatility of metals we have the data furnished by 
G. W. A. Kahlbaum? in a notable study of the subject. 
From this, certain anomalies appear, for example, the low 
volatility of tin. Among the intermetallic compounds, 
Berry ? succeeded a few years ago in showing that the com- 
pound MgZn, distils in vacuo at 600° and H. v. Wartenberg 
(loc. cit.) also studied the vapour tension of the compound 
Na,Hg. 

The problem of the existence in the vapour state of inter- 
metallic compounds is doubtless in close connection with 
the affinity relations of the said compounds about which, 
however, nothing is at present known. As we have already 
seen in the preceding pages, the bond of valency for these 
compounds is not very strong; but our observations are 
confined to the purely qualitative side of the subject. 

Admitting this weak bond, we can foresee that many 
intermetallic compounds which even in the liquid state 
undergo dissociation to a greater or less, but never negligible, 
degree, will be strongly or completely dissociated in the 
vapour state. 

The heat of formation of intermetallic compounds must 
have a considerable influence on their degree of dissociation. 
It is difficult to obtain data on the existence in the vapour 
state of compounds which are formed from their elements 
with considerable evolution of heat. 

1 Zeit. electro. Chem., 20, 443 (1914). 


2 Zeit. anorg. Chem., 29, 177 (1902). 
® Proc. Roy. Soc., A, 86, 67 (1911). 


NATURE OF INTERMETALLIC COMPOUNDS. 49° 


Areuing from a thermodynamic theorem of Nernst it 
may be assumed that an intermetallic compound whose 
boiling point differs by a few hundred degrees from those of 
its components will have a vapour tension experimentally 
determinable. 

If two monatomic vapours, A and B, combine to form a 
gaseous compound D, the reaction probably occurs with 
contraction. Applying Nernst’s principle the following 1s 
the equation of stability of the compound :— 


A+ B=D+Q+r,+A2 -Ap, 


where Q is the heat of formation at constant pressure and 
Au, An, Ay the latent heats of evaporation of A, B and D 
respectively. Then— 





fee pop. = b= 5 ner ee, 3 oe 1 log Ts, 
P,, P;, and P, being the partial pressures of the gases T’ and 
the absolute temperature. 

In this equation, the stability of the compound D 
increases with increase of the quotient on the left of the 
equation. The quantity @ may be determined by means of 
the heat of solution. The latent heats of evaporation may 
be obtained from Trouton’s rule, according to which the 
molecular heat of evaporation is proportional to the boiling 
point on the absolute scale. 

H. v. Wartenberg found that the gaseous compound 
MgZnzg 1s fairly stable at low temperatures but unstable at 
higher temperatures. The existence of the compound 
NasHg in the vapour state has been demonstrated. 

The fact that some intermetallic compounds can exist 1n 
the vapour state, although it does not solve the question of 
the nature of the linkage which binds together the constituent 
atoms of intermetallic compounds, offers some prospect of 
the possibility of explaining such combinations by the 


principles of the theory of valency. Between saline metallic 
C.M. 4 


50 CHEMICAL COMBINATION AMONG METALS. 


compounds and the true mixtures which make up inanimate 
nature there is no sharp break but rather a gradual 
transition which modern research has explored in the study 
of solid solutions and labile combinations (intermetallic 
compounds, additive compounds, etc.). 


CHAPTER IV, 


PuysicAL PROPERTIES. 


Influence exercised by the presence of Intermetallic 
Compounds on the physical properties of Alloys. 


In the preceding pages we have called attention to certain 
limitations of the thermal method in the complete study of 
equilibrium diagrams, above all, when it 1s a question of 
inferring the formation of one or more compounds. But, in 
addition to the thermal method, there is opened up a wide — 
field of investigation in the accurate study of certain physical 
properties of alloys, such as specific volume, thermal and 
electrical conductivities, hardness, magnetic properties, 
thermo-electric potential, electrolytic potential, heat of 
formation, specific heat, microscopic characters and crystal- 
line form. 

The presence of compounds always has some effect on 
the physical properties of alloys. A greater or less degree of 
discontinuity is often sufficient, not only to corroborate the 
results obtained by thermal analysis, but also to fill in any 
gaps which could not be explored by the thermal method 
alone. For example, the fact, placed in evidence by 
Kurnakoff, of the existence of intermetallic compounds 
with irrational maxima (?.e. compounds which do not obey 
Dalton’s law of constant proportions) has only been capable 
of development and interpretation by means of the study 
of physical properties. According to Kurnakoff, there should 
be, for every determinate compound, a corresponding dis- 
continuity or singular point in the curve of physical pro- 
perties and composition. When this discontinuity is lacking, 


a maximum noted on the curve obtained by the thermal 
4—2 


52 CHEMICAL COMBINATION AMONG METALS. 


method would correspond to a compound of variable com- 
position. It is the absence of this discontinuity in the 
electrical conductivity and compressibility curves in the 
bismuth-thallium and mercury-thallium alloys which led 
Kurnakoff (see Chapter V) and, more recently, his pupil 
P. Paulovitch! to postulate irrational maxima in these 
systems. 

In alloys where the formation of compounds does not 
take place, the physical properties are almost always linear 
functions of the composition, as in the case of specific 
volumes, or contmuous functions showing maxima or 
minima, as in the case of the electrical conductivity and 
hardness of solid solutions. 


Specific Volume, 


The specific volume of a mixture formed from two com- 
ponents is a linear function of the composition and can 
generally be calculated from the specific volumes of the single 
components ; it is, in short, an additive property. If a 
and y are the masses of the two components and v, and v, 
their specific volumes, the specific volume of a mixture is 
deduced easily from the mixture rule :— 








XLV, ae YVo ae 
a ! y V1 ole (V5 = V3) | = 
or, putting y =r 


0 =U, -+ ,. — 2))7. 


This equation means that in the mixing of the com- 
ponents there is no volume change. This rule is, however, 
not always strictly valid. Small deviations have been noted 
in the case of the formation of solid solutions and eutectic 
mixtures. It must also be mentioned in this connection 


1 Bull. Soc. Chim., (4), 20, 2 (1916). 


PHYSICAL PROPERTIES. 53 


that a linear relation can subsist in cases where the com- 
ponents form a continuous series of solid solutions. 

The formation of a chemical individual introduces a 
discontinuity into the curve of specific volumes. If for 
example the specific volumes of two components which do 
not combine are plotted for varying concentrations, they will 
form a straight line; if, on the other hand, a compound 
appears, the curve will consist of two branches which 
intersect in a point which, if secondary phenomena do not 
interfere, indicates the composition of the compound. The 
case 1s different where the compound forms solid solutions 
with one or both of the components ; the two lines of the 
preceding case are then intersected by a third line so that 
two points are obtained, neither of which correspond to the 
maximum of the compound. As a rough approximation - 
this maximum can be obtained by producing the two lines 
till they meet. The point of intersection should give the 
maximum of the compound. . 

The following arithmetical rule, deduced by Maey ! 
may be applied to a mixture of two compounds resulting 
from the union of two elements A and Bb. If xan y are the 
masses of the two elements in a mixture of the two com- 
pounds (1) and (2) formed from the union of the said 
elements, 71, ¥;,and 25, Ys, the masses of the elements in the 
two compounds, then 

= 2, + egand y= yy + Ys 
so that 
ees Yo Te. + Ye ' ae 


V1 (i= Te + Yo ) Y ae 
yt yy (t+ 41) + at Yes e+ y 


is the relative amount of the element y, 

















and —2— = r, are the relative amounts of y in the 





1 Zeit. phys. Chem., 29, 122 (1899) 


54 CHEMICAL COMBINATION AMONG METALS. 


T2  Yo 
ee eas) pi: 
is the relative amount of the compound (2) in the mixture. 
The relation can be stated as 


Petey Gar ty le ep te a) 
or in other words, the relative content of the mixture in 
one of two elements is a linear function of its content in one 
of the two compounds. 

Asa deduction from this simple relation it may be recorded 
that specific volume can be substituted in the calculation of 
atomic volume. We may consider, fer example, the mixtures 
of mercury with the alkah metals. 

If V, be the atomic volume of mercury, V, that of the 
alkali metal in the mixture, n, the number of atoms of mer- 
cury and n, the number of atoms of the alkali metal; and 
if V be the mean atomic volume of the mixture and R the 
relative atomic content in alkali metal, then 





two unknown compounds, while 





Va Rie ota 
Vee ee es =V,+(V,—V,)R 
ne eels 
e Nea > 


These two equations can also be obtained from the atomic 
weights of the elements comprising the mixture. For if 
M, and M, be the atomic weights of the elements and 
m, and m, their relative amounts in the mixture, 


m m 
i and 


M, M, 
and hence 








ig IE chs at Ma) 
= M, ee 





PHYSICAL PROPERTIES. 55 














Horey;, 
y Ving +t Vans YY M,71+ 0, My ny _ 01M, + Vy M, 
N1+ No N1 + No M,+ Ms, 
m,+m, n.M 1 
. = 2 : = UV Alive: 
Meg ee ‘5 


Putting v = a + br where a and b are two constants, by 
substitution | 

From this expression it is seen that V is a linear function 
of R. 

Maey has applied these relations to many alloys, even in 
some cases where compounds are formed. In the following 
table we reproduce some values from Maey for alloys which 


do not show sufficiently great deviations in their specific 
volumes for existence of compounds to be inferred. 


ALLOYS SHOWING CONTRACTION IN SPECIFIC VOLUME. 


























| Alloys. v=a-+ Dp. Ay. p-Av. s.. 
Bi — Cd -10181 + -0001373 p — -00015 51:8 — -001 
Ag — Bi 70955 + -000063 p — 0004 49-0 — 004 
Hg — Sb 07368 + -0001422 p — -0008 50:8 — -010 

| Hg — Sn 07366 + -0006345 p — :00091 Dosis.) = 009 

| 





ALLOYS SHOWING INCREASE IN SPECIFIC VOLUME. 








Alloys. v=a+ bp. AV. p-Av. —. 
Sn — Sb 13710 + -0001187 p + -0011 51-4 + -007 
Sn — Zn -13710 + -000010 p + -0005 75:0 + -005 
Pb — Cd 08791 + -0002763 p + 00035 8:3 + -001 
Pb — Sb -O8791 + -0006106 p + -00100 54-1 + +009 


























56 CHEMICAL COMBINATION AMONG METALS. 


ALLOYS SHOWING BOTH POSITIVE AND NEGATIVE DEVIATIONS. 














Av 
Alloys. v=a-+ bp. Av. p.4v. eae 
Bi — Sb -10181 + -0004715 p — 00013 37°] — -001 
+ -00003 22°7 + -0003 
Bi — Sn 10181 ++ -0003530 p + +00105 iss) + -010 
— -00058 62-5 — -005 
Cd — Sn 711544 + -0002156 p + -00063 80-5 + -005 
— :00012 14-7 — 001 
Pb — Sn 08811 +- -0004900 p + :00085 16-0 + -009 
— :00073 69-5 —-006 
Pb — Ag ‘08791 + .0000761 p -++ -00064 Led + +007 
— -00043 67-6 — 005 
Ag —Cu | -01591-+-000176 p | + -0007 56 | + -0074 
— -00003 50°35 | — -003 
Au — Cu 05191 + -000605 p + +0004 6-8 + -007 
— -00003 [991 == +0006 
Au —Ag 05191 -+ -0004309 p | +-00016 | 76:5 | + -002 
— :00007 12-0 — 001 
Au — $n °05191 + -000852 p + -00108 370 + 013 
— -00104 22°7 — O15 
Ir — Pt 04461 + -0000190 p + -00011 66°7 + 002 
— :00007 95°0 — 002 

















From the study of specific volume concentration curves, 
Maey’ has affirmed the existence of the following com- 
pounds :— 


SnAg, Sb,Cd, SuCu, CuCd, 
Au,Bis SbAg, CuZng AgHg 
AugPbs SbCu, AgZn, 

Sb,Zn, FeSb AgCd, or AgCd, 


The specific volume method has been applied by Maey to 
the study of the potassium, sodium and lithium amalgams, 
but the numerous compounds formed in these series have 
led to the results being partly untrustworthy. 

In the cadmium-arsenic alloys an example has been found 
of the existence of two compounds formed. with expansion. 


1 Zeit. phys. Chem., 38, 292 (1901) ; 50, 200 (1905). 





PHYSICAL PROPERTIES. 57> 


In this case solid solutions do not occur, at least within 
wide limits: it was found that the curve consisted of two 
straight lines intersected by a third. Here, the points of 
intersection give the maxima of the compounds. 

As a conclusion of these investigations we can affirm that 
the specific volumes of alloys which are simply mechanical 
mixtures can be calculated to within 1 per cent. by the 
mixture rule; deviations, when they occur are generally 
to be attributed to the formation of compounds. 

_ C. Hoitsema ' has made a contribution to the subject ina — 
study of the density of the copper-gold and gold silver alloys. 
As is known, the density is the inverse of the specific 
volume. In the following table are shown some values for 
the copper-gold alloys; the calculated specific volumes 
have been obtained by the mixture rule and are concordant 
with those experimentally found. 


CopPpER-GoLD ALLOYS. 

















: Specific volumes. 

ld Specific 
Ridge Branly at ——--———| Difference. 
soyacs Observed. Calculated. 

(100-0) (19-26) (05192) a = 
oY 17°35 °05764 05715 — 9% 
83°3 15°86 °06305 06244 - J-0,, 
75:0 14-74 06784 -06768 — °3,, 
58:3 12-69 -O07880 -07820 — +8,, 
25-0 10°035 *09965 09919 — °9,, 

0-0 (8°7) (-11494) ea a 























Specific Heat of Intermetallic Compounds. 


The energy content of solid bodies is a subject of great 
importance and is intimately bound up with that of crystal- 


1 Zeit. anorg. Chem., 41, 63 (1904). 





58 CHEMICAL COMBINATION AMONG METALS. 


line form. Domenico Guglielmini, in 1688 and 1705,! recog- 
nised that every substance has its own crystalline form, 
governed by definite rules. Among the many theories on 
the energy content of solid bodies is that of the uniform 
distribution of this energy. This has, however, recently 
been thrown in doubt by the investigations of Nernst and 
his co-workers on the relation between specific heat and 
temperature. 

The kinetic theory of the energy content of a monatomic 
body, which is the simplest case, postulates that the 
function : 


\CvdT 


is indicated by the oscillations of the atoms, which are 
supposed to be at rest at absolute zero. Ata given tempera- 
ture the atoms are in motion and, in an isotropic body, this 
motion occurs in three planes perpendicular to each other. 
With rise in temperature the energy content of bodies varies. 
For a solid body such energy is given by the displacement of 
the atoms from their equilibrium positions, or the localised 
potential energy. 

According to Nernst,? considering the case in which 
atoms revolve ina circular path about their mean positions, 
and assuming that the force attracting them to such posi- 
tions is proportional to the displacement,? the equation for 
the centrifugal force for an atom of mass m revolving with 
velocity win a circle of radius r is 


mM 
—w=—Ar 
; 


where A is the force per unit displacement attracting the 
atom to its position of rest. 


1 On the works of this founder of crystallography see Guareschi: Domenico 
Gugliclmini ¢ la sua opera scientifica. ‘Turin, 1914. 

2 The Theory of the Solid State. London, 1914, p. 11. 

3 Boltzmann: Vorles u. Gastheorie, I., 126. 


PHYSICAL PROPERTIES. 59 


The kinetic energy of the atom is 
m (ies 
5 ue A eee Ax, 


from which 


m m 
pe 
9 Ui = 5 Ua", 


which establishes the equality between kinetic and potential 
energy. Consequently, if it 1s known that the kinetic 


cet 
energy of a monatomic gas 1s 9 RT = 2-:98T per gram atom, 


from the above equation the atomic heat of a monatomic 
solid body 1s 

CU 3h == 0000, 
for 08a: 

This simply expresses the law of Dulong and Petit. 

For the content in heat energy of metallic compounds, as 
appears from two recent works of H. Schimpff* and F. 
Schubel,? the Neumann-Kopp law holds, according to which 
the molecular heat of a solid compound is equal to the sum 
of the molecular heats of the elements contained init. The 
specific heat, c, of a compound 1s calculated from the equation 


— nM,c,+ mM, c, 
~~ wi - mM 





where ¢,, ¢, are the specific heats, M,, M, the atomic 
weights and n, m, the number of atoms of the components 
in the compound. 

In metallic compounds, specific heat is an additive pro- 
perty. Before the study of metallic compounds had reached 
its present importance, Regnault * had shown that the specific 
heats of fusible metals followed the mixture rule at tempera- 
tures below the melting point, diverging therefrom at higher 


1 Zeit. phys. Chem., 71, 288 (1910). 
2 Zeit. anorg. Chem., 87, 101 (1914). 
3 Ann. Ch. Phys., (3), 1, 129 (1841). 


60 CHEMICAL COMBINATION AMONG METALS. 


temperatures. The recent investigations of Schiibel show 
the additive character of the specific heats of metallic 
compounds. 

The following table shows the results obtained by Schiibel 
for a number of definite compounds at temperatures below 
their melting points. 





Specific heats at 








Com- Melting 
pounds. | | Points. 
100° 200° S007 14002) 600" > 600? 
| | 
Cu,Mg| -1184 *1230 1283 *1365 ae SS (oT 
Cu, Al *1093 °1135 aha? °1205 | -1260 —. | 1050° 
CuAc -1310 1363 “1413 -1468 — — 625° 
CuAl, *1526 °1585 -1630 *1690— )"*1 690 = 590° 
Cu,Sb | -0815 0837 0860 “0890 — — 687° 


Cu,Sb | -0760 | -0784 | -0806 = ore eae ae 
AgMe | -0910 | -0942 | -0974 | -1004 | -1042 | -1070 | 820° 
Ag,Al | -0695 | -0724 | -0745 | -0762 | 0798 | 771° 
Ag,Al | -0763 | -078 | -0806 | -0831 | -0868 +0913 | 721° 
Ae.Sb | -0560 | -0574 | -0630 = = 559 
Modu, 21180 | 1234.) cpGa2 21450 4) ey BOS 
Ni,Mg | +1305 | +1385 | +1424 | +1460 | -1480 | -1508 | 1145° 
Co,Sn | +0824 | -0876 | -0900 | -0926 | -0944 | -0962 | — 
Ni,Sn | -0836 | -0872 | -0907 | -0940 | -0972 +1002 | 1162° 
FeSi | -1465 | +1540 | -1600 | +1645 | -1690 | -1720 | — 
Nisi ae = 1469 | -1523 | -1572 | -1615 | — 
Ni,Si | -1190 | -1250 | -1290 | -1320 | -1355 | -1386 | — 
Mg,Si | +2250 fe -Q45D Ee + | +2620 11102" 


| 


i) 
ee) 
“I 
bo 





























As a result of the preceding data it appears that the com- 
pounds Cu,Mg, Cu,Al, CuAl,, AgMg, Ag,Al, MgZn,, Co,Sn, 
follow the Neumann-Kopp law to within 2 per cent. Other 
compounds show greater deviations ; the compound Ni,Sn | 
shows a deviation of about 7-3 per cent. 

From the data given on p. 61 it appears that the Neumann- 
Kopp law is, especially for high temperatures, an approxi- 
mate statement. The divergences between the observed 
and calculated values are independent of the temperature 
for nearly half the compounds shown. We shall refer to a 





Mo.LECULAR HREATS OF CERTAIN 


PHYSICAL PROPERTIES. 











Cu.Mg 


Cu. Al 


CuAl 


CuAl, 


Cu,Sb 


Cu.Sb 


AgMg 


Ag.Al 


MgZn, 


Nip Mg 





61 


METALLIC COMPOUNDS 


























ein gan ate tg ct 


bo bo 


DEN SSCSSSENWUAAAINSS 








400° | 500° 
20-69| — 
Per 
0-01 = 
qo 
26-26 | 27-46 
26-07 | 26-71 
+ 0:19 | + 0-75 
+0-7 | +28 
ego) 
igs | = 
+017) — 
oo he 
19-61 | 19-22 
19-84 | 20-27 
—0-23 | — 0.35 
a eee 
are ee 
o00e) 
21-68), = 
oe = 
13-26 | 13-79 
13-26 | 13-81 
es Cae iy 
O@.. |=20-2 
26-73 | 27-43 
25-89 | 27-16 
+ 0-84 | + 0-27 
ee ae ee 
20-18 | 21-08 
19-49 | 20-38 
+ 0-69 | + 0-70 
+35 | +35 
20-70 | 20-99 
21-46| 21-77 
== 0-76\--0°75 
= 35 |= 396 





(ScHUBEL). 
Deviations of observed from calculated values. 
Mol. —150° | —100° | 0° 100° | 200° 
obs.) 12-81] 14-73] 17-13] 17-95] 18-65 
calc.) 12-88| 14:89] 17:37] 18-11] 18-68 
diff. — 0-07 | — 0-16 | — 0-24 | — 0-16 | — 0-03 
oF 0006 led fa Wide 00s | 08 
obs.| 16-28] 19-08) 22-60] 23-82) 24-73 
calc, 16:58| 19-48} 23-00] 23-98| 24-76 
diff. — 0-30 | — 0-40 | — 0-40 | — 0-16 | — 0-03 
Falt—d Bt lea 0'0 teat, ea 0eg Oil 
obs. 7-58] 9-10] 11-10) 11-88] 12-36 
calc. 8.00] 9-52] 11-42} 12-02] 12.48 
diff.) — 0-42 | — 0-42 | — 0-32 | — 0-14 | — 0-12 
OE yO ee eae cena 
obs., 11-70) 14:07| 17-04] 17-98] 18-67 
eale., 11-71] 14:07] 17-05] 18-06) 18-82 
diff.|—0-01| 6 |—0-01|/—0-08 |—0-18 
ee Use Oe toe eed ce 
obs., 19-44] 21-60| 24-28] 25-33] 26-01 
calc.) 17-82] 20-33] 23-31] 25-06] 24-71 
diff.) -+ 1-62 | + 1-27 | + 0-97] + 1-27] + 1-30 
%|/+9-0 (+62 |4+41 |452 | 4+5-2 
obs.) 14-40] 15:99; 17-97] 18-79] 19-32 
eale, 13-53] 15-35} 17-52] 18-08| 18-57 
diff.| + 0-87 | + 0-64 | + 0-45 | + 0-71 | + 0-75 
%)+6-4 | +41 142-6 |+3-9 | 440 
obs. 8-76] 9-90) 11:36] 12-02] 12-46 
calc, 9-27| 10-39] 11-80] 12-23] 12-54 
diff.| — 0-51 | — 0-49 | — 0-44 | — 0-21 | — 0-08 
%|—55 |—4-7 |—3-7 |—1-7 |—0-6 
obs. 19-08] 20-92) 23-36] 24-56| 25-40 
calc, 18-62| 20-92| 23-66] 24-28] 24-76 
diff, + 0-46] 0  |—0-30| + 0-28 | + 0-64 
eee ol Ob ees oo. OG 
obs.) 13-77) 15-45| 17-70] 18-53] 19-07 
calc. 13-65] 15-46| 17-65] 18-20] 18-62 
diff.) + 0-12 | 0-01 | + 0-05 | + 0-33 | + 0-45 
%\+09 | 0 |+03 | 41-8 | +2-4 
obs., 20-48| 22-44) 24-52 | 24-85 | 25-47 
calc, 19-86| 21-67| 23-97| 24:36] 24-71 
diff.) + 0-62 | + 0-77| + 0-55 | + 0-49 | + 0-76 
%®ji/+3:1 (43:5 |4+2:3 |4+2:0 |4+3-1 
obs.| 13-71] 15-27) 17-37| 18-31] 19-15 
calc. 13-98| 15:57) 17-71| 18-69| 19-44 
diff.| — 0-27 | — 0-30 | — 0-34 | — 0-38 | — 0-29 
FE Os ee eae ih Gs es ene eeen tas 
obs — | 14-18] 16-80] 18-50] 19-64 
calc, — | 14:51] 17-91] 19-45| 20-92 
i se on 128 
Se 6s | 








62 CHEMICAL COMBINATION AMONG METALS. 


rational interpretation of the divergences shown with rise in 
temperature in the following pages. 


Atomic HEATS OF CERTAIN METALLIC COMPOUNDS 


(FROM SCHUBEL.) 























Compounds) 100° 200° | 300° | 400° | 500° 600° 
| | | 
ies | | 
Cu,Mg | 5-98 6-22 6-48 6-89 = = 
CusAl | 5-95 6-18 6-36 6-56 6-86 ae 
CuAl 5°94 6-18 6-41 6:66 — a 
CuAl, | 5-99 6-22 6-40 6-54 5-64 = 
Cush: | 683 6-50 6-68 6-91 = = 
Cu,Sb | 6-26 6-44 6-65 ae — — 
AgMe | 5:89 | 6-23 6-44 6-63 6-89 7-07 
Ag,Al 614 | 6°35 6°54 6:68 6°86 7-00 
Ag, Al 6°17 6:36 6°53 6°73 7:03 7:40 
AgSb | 6-21 6-37 6-99 ae — 
MeZn, 6-10 6:38 6-68 7-48 — a5 
Ni,Mg 6-17 6-55 6-73 6-90 6-98 7-12 
Co,Sn 6°51 6-92 7:10 7°33 7:46 7:60 
Ni,Sn 6°17 6-48 6:70 6-95 718 1°39 
esr |. 20:16. | 9646 6-74 6-93 fiat 7°25 
NiSi | Paley Bi aes 6-39 6-64 6-85 7:04 
Ne St Orit he 6-07 6:27 6-40 6-59 7:67 
MgSi 5-78 6-31 = = 6-79 
| | | 














The relation of atomic heat to temperature above 100° is 
generally almost lear. If the above values are plotted 
along with the known values for the pure metals it will be 
seen that the behaviour of intermetallic compounds is 
perfectly similar to that of pure metals. 

Inasmuch as the figures quoted do not show a perfect 
concordance between observed and calculated values, the 
Neumann-Kopp law must be considered as an approxima- 
tion, particularly at high temperatures. 

Planck’s* quantum theory, proposed in his researches 
on the phenomena of radiation has been generalised by 


1 Theorie d. Warmestrahlung, p. 157. Leipzig, 1906. 


PHYSICAL PROPERTIES. 63 


Kimstein + for the movements of atoms; it gives a rational 
explanation of the deviations from the law of Dulong and 
Petit, which forms the foundation for that of Neumann- 
Kopp. 

Kinstein’s formula for the total energy content W of a 
gram atom is given by the equation, deduced from the ordi- 
nary equations for the distribution of energy, 








= By 
Vas “By 
eT —1, 
and for atomic heat, differentiating with respect to T :— 
ald (ae) 

| ines 5 pe fee & 

a) 
e T —I 


According to the quantum theory, definite limits are 
assigned to the oscillations of an atom about its equilibrium 
position. In the case of a solid monatomic body it may be 
assumed that its molecules are surrounded by a gas which 
may be considered monatomic for simplicity. The molecules 
of this gas oppose the oscillations of the atoms of the solid 
body, producing thereby a condition of equilibrium. For a 
monatomic gas the number of oscillations is mil; it can 
move freely by its kinetic energy according to Maxwell’s 
conception. But for a solid body or any other union of 
molecules the quantum theory leads to other results. 
Einstein’s formula, which gives the specific heat as a function 
of the temperature, leads to a simple qualitative result. 
Quantitatively there are divergences between theory and 
observation which increase at low temperatures. 

Nernst and Lindemann? have amended the formula of 
Einstein, introducing in addition to the number of oscilla- 


2 V . . ‘ 
tions r a second number which gives values more in 


1 Ann. d. Phys., 22, 180 (1907). 
2 Ber., 43, 26 (1910). 


64 CHEMICAL COMBINATION AMONG METALS. 


accordance with experiment. The Nernst-Lindemann 
formula is the fellowing :— 

[Beaks a ee Gea 
pee UE Fp (aa) Tet) 


ie : a ie c oe AS 

















Although it has been shown necessary to introduce into 
Einstein’s formula a greater number of oscillations, the value 


Vs . ; 
—in the above formula has no theoretical basis. 


2 


Other theoretical possibilities with regard to the relation 
of specific heat and temperature have been discussed by 
Debye + and Duclaux.2, We must, however, limit our treat- 
ment of the subject to the short outline given above. 


Electrical Conductivity. 


The problem of the electrical conductivity of alloys has 
become of considerable importance with the development 
of modern metallography—an importance both theoretical 
and practical because alloys with constant and small tem- 
perature coefficients are of great use in electrotechny. The 
first exhaustive study of this subject was made by Matthies- 
sen. In his earlier researches Matthiessen found that 
binary mixtures of metals can be divided into two groups ; 
in the first the conductivity, o, 1s an additive property 
as in the case of alloys of lead zinc, tin and cadmium ; in 
the second group the conductivity is less than that calcu- 
lated by the mixture rule, as in the case of alloys of copper, 
silver, gold, aluminium, bismuth, platmum, antimony, iron 
and others. These two types of conductivity curves are 
shown in Fig. 19. The abscisse represent the percentage 
of the second component and the ordinates the con- 


1 Ann. d. Phys., 39, 789 (1912). 

2 C. R., 155, 1015, 1509 (1912). 

3 Pogg. Ann., 108, 428 (1858); 110, 190 (1860); 116, 369 (1862) ; 122, 19 and 68 
1364). 


PHYSICAL PROPERTIES. 65 


ductivity. The straight line I. indicates that in a mixture 
of two metals the conductivity can be calculated by the 
mixture rule, 1.e., the conductivity of the alloy is the sum 
of the single conductivities of its constituents obtained 
from their relative proportions. Curve II. shows the 
course of conductivity in alloys of the second group. 

If a quantity of an element of the second group be added 
to a metal of the first group the conductivity curve will be 





a 


= 


eS 





poeta Oy yey PSO I IU gM 














pre Volunre ee 


Fie. 19. 


lowered appreciably and the curve will be of the type III. 
Curve IV. represents the case of the formation of a 
compound. 

Among the investigations carried out on the conductivity 
of metallic alloys must also be mentioned those of Le 
Chatelier + and Liebenoff.2 Lord Rayleigh? has also dis- 
cussed the matter on the theoretical side. 

1. R., 112, 40 (1891) ; 126, 1709 (1898). 


2 Zeit. Hlektr., 4, 201 (1897—98). 
3 Nature, 54, 154 (1896). 


66 CHEMICAL COMBINATION AMONG METALS. 


Le Chatelier attempted to give an explanation of the 
diverse behaviour of the metals of Matthiessen’s first and 
second groups. If an alloy is a “ mixture of crystals ” of 
two metals, the conductivity may be calculated by the mix- 
ture rule ; but if it forms “ crystals of mixture ”’ the values 
of the conductivity are then different.’ Le Chatelier 
further noted that the addition of small quantities of non- 
metals, such as phosphorus, carbon and arsenic, exercised 
a great influence on the conductivity of certain metals. The 
conductivity of iron, for example, is greatly altered by the 
addition of small quantities of carbon.? 

The electrical conductivity method has been used of late 
years to define the existence of various intermetallic com- 
pounds. By the investigations of Guertler,? of Kurnakoff 
and Zemezuzny * and of Stepanoff,> it has become one of 
the most valued methods of investigation for the solution 
of problems left unsolved by the thermal method. The 
experimental methods followed in the investigations men- 
tioned are based on measurements of conductivity or of 
specific resistance. 


MATTHIESSEN’S RULE. 


‘If the relative increase of conductivity between 0° and 100° 
be expressed by the equation— | 


Pita 100 100 Ci00 — 2o 


3 
oo Pio 





where %, % are the conductivities at 0° and 100° respec- 


tively, and 2%, i, the specific resistances, then for pure 
metals P (c) = 29. 


Ifo,, and P,, (7) are the numerical values calculated by 


1 Cf. Chiwolson. T'raite de Phys., IV., 1003 (1910). 
2 Cf. Benedicks : Zeit. phys. Chem., 40, 545 (1902). 
3 Zeit. anorg. Chem., 51, 397 (1906), 54, 58 (1907). 

4 Ibid., 54, 149 (1907) ; 60, 1 (1908). 

5 Ibid., 60, 209 (1908) ; 78, 1 (1912). 


PHYSICAL PROPERTIES. 67 


the mixture rule Matthiessen’s rule is expressed by the 
following equation :— 





a ee) 
Tn a ie (o 
The value of P,,, (7) is about 29. 


th 
. 


Barus’ Rute. 


Barus,’ from the expression 


P () = 100 eet hee 100 = 1m, 
0 100 


obtained for pure metals P (*) = 41. 








eee Comet sy ry SES PS 











—) Concentrionine 


Fig; 20, 


This equation has since been discussed and amended by 
Guertler who has adapted it to many experimental diver- 
gences ; it retains, however, its empirical character. 

We pass on to state certain general relations established 
by Guertler in his interesting investigations. With regard 


1 Amer. Journ, of Sci., (3), 36, 427 (1888). 


~ 


v2 


68 CHEMICAL COMBINATION AMONG METALS. 


to the nature of conductivity diagrams the following rule 
holds :— 

When, in a series of alloys between two metals m com- 
pounds are formed, the diagram consists of m-+ 1 binary 
systems. 

Generally, compounds have a conductivity iess than that 
of their most conductive component." When a compound 
forms solid solutions with both components the diagram 
showing relation between conductivity and composition 
assumes the form of Fig. 20. 

The conductivity method has been of great help in the 
study of equilibrium diagrams, especially in cases where 
compounds are formed. In the following table are shown 
some systems studied both thermally and by the method 
of electrical conductivity. The results, as will be seen. 
are very concordant :— 











Formule of compounds deduced. 

System. 
By thermal method. By ee 

Au — Sn AuSn | AuSn 

AuSng AuSn, 

AuSn, | AuSn, 
Au — Pb AuPb, AuPb, 
Cu — Sn Cu,Sn | Cu,Sn 

Cu,Sn Cu,Sn 

CuSn | CuSn 
Cu — Sb Cu,Sb Cu,Sb 

Cu,Sb Cu,Sb 
Sb — Sn SbSn SbSn 














Apart from the direct measure of conductivity or specific 
resistance of intermetallic compounds, a factor which is of 
ereat importance and which has entered into common use 


1 A rule noted by Matthiessen in his investigations already recorded. 


efficient has 


PHYSICAL PROPERTIES. 


is the temperature coefficient of conductivity. This co- 


been determined for intermetallic 




















compounds. Some values are shown in the following 
Table :— 

Alloys. Compounds. oe eee 
Mg — Pb Me,Pb 00250 
Mg — Sn Mg,Sn .- 00445 
Mg -- Cu MeCu, 00316 

Mg,Cu 00365 
Mg — Zn MgZn, 00290 
Mg — Bi Mg,Bi, 00370 
Mg — Ag MeAg 00310 

MgAg, 00309 
Mg — Cd MeCd 00417 
Sn — Sb Sn,Sh, 00361 

SnsSb 00343 
Cu — Sn Cu,Sn 00350 

CuSn 00300 
Cu — Zn CuZn 00360 

CuZn, 00408 

CuZng 00355 
Cu — As Cu,As 00250 








Like many other physical constants, the temperature 
coefficient of conductivity is a characteristic function 
of the composition of an alloy. The observations made 
on p. 64 on conductivity curves hold also for this 
constant. 

Alloys which have a small temperature coefficient are very 
important from the technical point of view; they are 
generally used in the construction of resistance cells. Such 
alloys do not, however, correspond to any definite compounds 
but are really solid solutions. Where solid solutions are 
formed between two metals, the curve passes through a 
minimum and so the alloys used in practice correspond 
pretty closely in composition to that indicated by such 
minimum. 


70 CHEMICAL COMBINATION AMONG METALS. 


Magnetic Properties 


The magnetic properties of alloys have been used in some 
cases to throw additional ight on the formation of com- 
pounds; but the information which we possess on this 
branch of the subject does not permit the establishment of 
any general rules. Up to the present, the chief studies have 
been made on those alloys which have some practical 
importance. | 

The most important work on metallic compounds 1s that 
of Tammann,! but before discussing his results in detail, it 
will be well to summarise the fundamental principles of the 
magnetic properties of metals. 

Although, according to Faraday,? magnetic bodies can be 
classed as paramagnetic or diamagnetic, it may be more 
useful to follow the classification of Chwolson * who divides 
substances into two groups: (1) the ferromagnetic or 
strongly magnetic substances such as iron, steel, nickel, cobalt 
and certain alloys; and (2) weakly magnetic substances ; 
this group includes both paramagnetic and diamagnetic 
bodies. 

In alloys, magnetic properties vary according to the nature 
of the constituents. It is most particularly of interest to 
follow the variations where ferromagnetic bodies are in alloy 
with substances of different magnetic nature. 

Tammann has given two rules which have an almost 
general validity :— 

I. Binary combinations of ferromagnetic metals with other 
metals are nearly always non-magnetic or only slightly 
magnetic. 

This rule has been deduced from the study of the magnetic 
properties of alloys of iron, cobalt and nickel with silicon, 
tin, aluminium, antimony, bismuth, magnesium and zine. 
In this series of alloys the following compounds occur :— 

1 Zeit. phys. Chem., 65, 73 (1909). 


2 Phil. Trans., 136, (1846); Pogg. Ann. 68, 105 (1846). 
3 Traité de Phys., IV., 830, 884 (1910). 





PHYSICAL PROPERTIES. 71 











Fe. Co. Ni. 
FeSi | Coo Co.Sie; U0el; Cools, | Nisei, Nissi; Nissi, Nish, 
CoSi, NiSi, 
Fe, Sn, Co,Sn, CoSn Ni,Sny, Ni,Sn, Ni,Sn (?) 
FeAl, CoAl, Co,Al;, CosAls NiAl,, NiAl,, NiAl 
FeSb, Fe,Sb, | CoSb, CoSb, Ni,Sb,, NiSb, Ni,Sby, NiSb 
— —- NiBi, NiBi, 
— = Ni,Mg, NiMg, 
FeZn,, FeZn, | CoZn, NiZn, 














K. Honda t in a further study of the alloys nickel-chro- 
mium, nickel-tin, nickel-aluminium, cobalt-chromium and 
iron-vanadium has confirmed this rule of ‘Tammann. 
A. Friedrich ? has found that it only holds for binary com- 
binations of ferromagnetic metals with other elements of a 
purely metallic character; the compounds formed with 
elements of a metalloidal character are magnetic. Such, for 
example, are the following compounds :— 


CosAsq, Fe,P, Fe,P, Fegs. 


The borides of iron, cobalt and nickel are magnetic, 
although not to a high degree, as Moissan 3 has observed. 

II. Alloys consisting of mixed crystals in which a ferro- 
magnetic metal preponderates are magnetic ; those wm which 
the ferromagnetic metal does not act as solvent (1.e., 18 present 
in relatively small amount) are non-magnetic. 

This rule also has been confirmed by Honda. An instance 
of it is given by the amalgams of the three ferromagnetic 
elements. Nagaoka ‘* found that the amalgams of iron and 
cobalt are strongly magnetic, while the nickel amalgams as 
H. Wiinsche ® has observed, are ouly shghtly magnetic. 

A systematic study is desirable of magnetic properties in 

1 Ann. d. Phys., (4), 32, 1003 (1910). 
2 Metall., 3, 129 (1908) ; 5, 593 (1908). 
® C, R., 120, 173 (1895) ; 122, 424 (1896). 


Wied. Ann., 59, 66 (1896) ; Zeit. phys. Chem., 22, 641 (1897). 
5 Ann. d. Phys., (4), 7, 116 (1902). 


72 CHEMICAL COMBINATION AMONG METALS. 


relation to chemical composition ; the subject 1s somewhat 
obscure by reason of the numerous anomalies encountered 
in practice which have to be explained by particular reserva- 
tions contrary to the spirit of general principles. 

An interesting phenomenon which has recently been used 
in the theoretical treatment of the metallic properties of 
metals is presented by ferromagnetic alloys composed of 
non- “magnetic metals. 

Hogg,! in 1892, had observed that while certain ferro- 
manganese alloys are non-magnetic, they acquire by the 
addition of aluminium approximately the same magnetic 
properties as iron. Heusler? subsequently noticed the 
same phenomenon in the manganese-copper alloys, which 
are non-magnetic but become magnetic by addition of 
aluminium, tin, bismuth, antimony, arsenic or boron. The 
most strongly magnetic alloys, however, are those obtained 
by addition of aluminium in the exact proportions required 
for the two compounds Mn,Al and CugAl. 

Heusler has, therefore, suggested that the ferromag- 
netism of such alloys is only to be sought in the chemical 
compounds resulting among the constituent metals. These 
combinations would have the following formula :— 

A Win ge 

The ferromagnetism of these compounds has been dis- 
cussed by Richarz, a pupil of Heusler, from the point of 
view of the electron theory; he supposes that electrons 
have a greater degree of mobility in compounds than in 
pure metals. This supposition, though not well established, 
fits in with J. J. Thomson’s theory, according to which the 
electrical conductivity of metals is due to a apeuore of 


electrons.’ 
Ki. Wedekind,’ in a study of the magnetisation of mag- 


1 Chem. News.. 66, 140 (1892). 

2 Zeit. angew. Chem., 17, 260 (1904); Richarz and Heusler, Zeit. anorg. Chem., 61, 
265 (1909) ; 65, 110 (1910). 

3 Cf. The Corpuscular Theory of Matter, p. 49. London, 1907. 

4 Zeit. phys. Chem., 66, 614 (1909). 


PHYSICAL PROPERTIES. 73 


netic compounds composed of non-magnetic elements, has 
also recognised that ferro-magnetism is not only an atomic 
property as in the case of iron, nickel and cobalt, but may 
also be a molecular property. It may further be mentioned 
that the elements which are magnetic either in alloys or 
compounds are found in a definite region of the Periodic 
System, 2.e., at the end of the fourth horizontal series ; they 
are elements whose atomic weights le between 52:1 and 59, 
chromium, manganese, iron, nickel and cobalt. 


Electrolytic Potential. 


Electrolytic potential in the same way as the other 
physical properties hitherto considered is a function of 
composition ; a knowledge of this quantity is often of great 
value in the investigation of metallic alloys. It is, further, 
of practical importance in so far as it bears on the corrosion 
of alloys in electrolytic liquids. We shall allude briefly to the 
principal deductions made in this branch of research. The 
actual knowledge which we have of the conditions of 
equilibrium between an electrolyte and an alloy contaiming 
a chemical compound capable of forming solid solutions is 
somewhat scanty. 

The most valuable investigations on electrolytic potential 
are those of W. Reinders ' and N. Pushin.2 The theoretical 
ideas which have been used in these studies are based on the 
concept of electrolytic solution pressure introduced into 
physical chemistry by Nernst * in 1889. 

When a metal is immersed in a solution of one of its salts 
a difference of potential is set up between metal and solution ; 
from this difference of potential originates electromotive 
force. 

Theoretically, however, the problem is more complicated 
than it appears at first sight. In fact, in the interpretation 


1 Zeit. phys. Chem., 42, 225 (1903). 
2 Zeit. anorg. Chem., 56, 1 (1908) ; 62, 34 (1909). 
3 Zeit. phys. Chem., 4, 150 (1889), 


74 CHEMICAL COMBINATION AMONG METALS. 


of the case above mentioned it is necessary to take account 
of the opposition of the ions of the salt which tends to 
neutralise the solution pressure of the metal ; this opposing 
force is, of course, the osmotic pressure of the ions of the 
~ electrolyte.t 

Laurie* and M. Herschkovitch * studied different alloys 
immersed in a solution of a salt of one of the component 
metals. They noticed in the curves for electro-motive force 
a number of discontinuities, particularly in the alloys 
copper-tin and gold-tin, where the discontinuities corre- 
sponded to the compounds Cu,Sn and ‘AuSn respectively. 
In these studies, however, Laurie did not take into account 
the concentration of the electrolyte, a factor of fundamental 
importance if reliable generalisations are to be made. 

Herschkovitch used a normal solution of a salt of the more 
positive metal. He draws attention to the principles of the 
phase rule and shows how they can elucidate the variations 
of potential in alloys. These variations can be grouped in 
the following four cases :— 

I. The two metals separate in a pure state from thew 
solutions. 

Il. The metals are soluble wn the solid state to a limited 
degree. 

In this case Gibbs’ principle may be applied, namely, that 
“the potential of all the components in the total of the 
system is constant.” 

III. The metals are completely soluble. The potential 
varies continuously with the composition. 

IV. In the solidification of fused mixtures of the metals a 
new phase (compound) vs formed. For n compounds there will 
be “ n”’ discontinuities on the potential curve. 

Herschkovitch, from studies of the form of potential 


1 Cf. “ Elettrochimica,” G. Carrara, in “‘ Nuova Encicl. di Chimica,” I. Guareschi, 
p. 494, Vol. I. (1906). 

2 J.C. S., 58, 104 (1888); 55, 677 (1889); 65, 1031 (1894). Phil. Mag. (5), 38, 
94 (1892). 

3 Zeit. phys. Chem., 27, 123 (1899). 


PHYSICAL PROPERTIES. 75 


curves, deduced the formation of the followmg binary 
compounds :— 
ZnSb,, Zn,Ag, Zn,Cu, SnAg, and SnCusg. 

Reinders’ Classification.—Reinders’ work, already men- 
tioned, is the most important theoretical contribution to 
our knowledge of the variations of electrolytic potential 
among metallic alloys. We shall describe briefly the 
different cases that can arise in alloys constituted of simple 
conglomerates or solid solutions. More particular attention 
will be given to the case in which a compound occurs. 

I. The two metals form solutions from which the components 
separate wm the pure state. Let M,, M, be the two metals and 
M,Z, M,Z, the corresponding salts. The electrolyte is 
assumed to be a homogeneous-phase. The difference of 
potential between the pure metal M, and the electrolyte 
containing M,Z, is calculated from Nernst’s ! formula :— 


x Bete 
eee ca Spy’ 


where P, is the electrolytic solution pressure, p, the osmotic 
R 
pressure of the cations M,, 1, the valency of M,, P the electro- 


lytic constant of gases and 7 the absolute temperature. 
When part of the ions of M, are substituted by ions of Mg, 
p, becomes smaller and hence x, becomes greater. The same 
argument applies to x; the difference of potential between 
the metal M, and a solution of M,Z is influenced by the 
presence of ions of M, as in the first case. For equilibrium 


tae ee 

Representing graphically the values x, 7, as a function of 
the composition of an electrolyte in which the total concen- 
tration of the ions is constant, the curve shown in Fig. 21 is 
obtained. A point in the line A D gives the difference of 
potential and the concentration of the electrolyte in equili- 


1 Zeit. phys. Chem., 22, 539 (1898). 


7 CHEMICAL COMBINATION AMONG METALS. 


brium with the metal M, ; similarly a point in B D gives the 
difference of potential and the concentration of the electrolyte 
in equilibrium with the metal M,. At the point D the electro- 
lyte is in equilibrium with both metals. For this point 


Ly = Los or 


— loo — = — loo —;, 
co) Or4y 
ny ae ale Be 
or 
ni ee 
Be Ge 
Pr P2 


and putting n, = no, 


Py: P. = py: po 











M, ; Me 


RIGS 2t. 





The ratio of the vwone concentrations in the equilubrvum con- 
dition 1s equal to the ratio of the electrolytic solution pressures. 

Il. The two metals form mixed crystals with each other. In 
this case the electrolytic solution pressure of M, is lowered 
by presence of M,; when in the metallic phase there are 
x atoms of M, and 1—z atoms of M, (a being very small), 
the lowering of the solution pressure is proportional to the 
number of molecules of the second metal which are in the 
solution. The solution pressure of the first metal 1s 


PHYSICAL PROPERTIES. 77 


P’ (1—2) and of the second Ka, in which K is an unknown 
factor. For equilibrium— 


nv ng, 


vos Ku 








5) 











ae = Op, 
or 
VP1 Vo a) 
atid: 1s. 
Pap 
Die eee 











My _ Ms 








HIG: 22. 


which means that the ratio of the ions in the electrolyte is, in 
atomic proportions of the metals, as i: P’. If the two 
metals form a continuous series of mixed crystals the 
potential curve assumes the form of Fig. 22, in which the 
continuous line represents the metallic phase and the dotted 
line the corresponding electrolyte. When there is a gap in 
the series of mixed crystals the two cases represented in 
Figs. 23 and 24 are exemplified. ‘The two components form 


78 CHEMICAL COMBINATION AMONG METALS. 


two series of solid solutions ; between the limits C and D the 
two metallic phases are in equilibrium. At FE the electrolyte 
co-exists. The type represented by Fig. 23 has been found 
by Herschkovitch + in the cadmium-tin and cadmium-lead 
alloys. The type shown in Fig. 24 has been met with by the 
same author in the zinc-tin and zinc-lead alloys and also by 
Jaeger 7 and Bijl? in the cadmium amalgams. 

Ill. The two metals form a compound. If the compound 
forms ions of its own composition the curve shows a maxi- 





























B 
ae 
c £ 
Ves = 
My Me My Ma 
Fic. 23: Fia. 24. 


mum as in Fig. 25. The solution tension of the compound, as 
in the case of a pure metal, is a specific constant. Indicating 
it by P,.. we obtain by Nernst’s formula— 
c= eee ofaeal 
eee, to 8 ise 
The ions of the compound are dissociated into the ions of 
the components, and if in the component there are a atoms 
of M, and b atoms of Mg, equilibrium will exist when 
Pr’ Po’ = K pyr. 
If the total concentration of the ions p,; + P»2 18 constant, 
2 Loc. cit. 


2 Wied. Ann., 65, 106 (1898). 
3 Zeit. phys. Chem., 41, 641 (1902). 


PHYSICAL PROPERTIES. 79 


Pi, reaches a maximum when p,:p,—a:b. In other 
words x reaches a maxvmum* when the ratio of the ons M, and 
M, w the electrolyte 1s equal to the ratio of the metals in the 
compound. ‘This case is indicated in Fig. 25. Along AG 
the potential is that of the electrolyte in equilibrium with 
pure M,; Gis anon-variant point in which the electrolyte 
of that composition is in equilibrium with M, and the 
compound M,M,. ‘The solid phase in equilibrium with 
electrolytes lying between G and Kt is the compound 














‘ 
' 
' 
' 
--2--e-- 
' 


\ 
l 
M, M, 
Fig. 25. 


M,Mg, and the potential follows the dotted curve. K is 
another non-variant point in which the compound M,M, and 
the pure component M, co-exist with the electrolyte. Along 
KB the electrolyte is in equilibrium with component M,. 

If n compounds are formed between the two metals M, 
and M,, for the point corresponding to each compound there 
occurs in the curve a fall of potential, so that there are n falls 
of potential as Herschkovitch stated. 

Reinders discusses also the cases in which the compound 
forms series of mixed crystals with the components M, and 











1Thus in Reinders’ paper. It would appear, however, that when pj. is a 
maximum, x should be a minimum.—TRANSLATOR’S NOTE. 


80 CHEMICAL COMBINATION AMONG METALS. 


M,. From what has been said already, however, the form 
of the potential curve will be quite clear in this as in the other 
cases, since the diagram is a combination of the types 
comprised in it. 

The complications which may occur in potential curves 
when, in addition to a compound, other variable phases 
appear with more or less wide limits, render the method 
somewhat unreliable, so that it is not always possible from 
observations of potential to deduce the true composition of 
the compound. 

A. Sucheni,! in a study of the potential of thallium amal- 
cams, noted that the compound Hg,T! formed solid solutions 
with mercury at an atomic concentration of 33-3 per cent. 
of thaliuum. The electromotive force increases up to the 
concentration of the compound, after which it remains con- 
stant. L. Cambi? has recently used the measurements of 
electrolytic potential to corroborate the equilibrium diagrams 
of the calcium and magnesium amalgams made from thermal 
data (see Chapter V). 

In the following table are shown some results obtained by 
Pushin in the study of the electrolytic potential of various 
binary alloys in which definite compounds exist. These 
results are not always in accord with those obtained by the 
thermal method. 














System. Compounds found by Pushin. Compounds now admitted. 
Ag-Se Ag»Se Ag.Se 

Ag-Te | Ag Te AgeTe, AgTe 

Cu-Te CuTe, Cu.Te Cu,Te, CusTe 

Pb-Te PbTe PbTe 

Sn-Te SnTe SnTe 

Sn-On SnCus, SnCu, snCus 

Sn-Ag SnAg,, Ag,sn or Ag;Sn SnAg, 

Sn-Au SnoAu, SnAu SnAu, Sn.Au, Sn,Au 
Zn-Cu Zn,Cu, Zn,.Cu, ZnCu, ZnCus ZnCu, ZnsCuyg 

Zn-Ag | ZngAg, Zn,Ag, ZneAg, ZnAg | Zn2Ag;, ZnAg, Zn;,Ag», Zn;Age 
Zn-Au Zn;Au ?, ZneAu, ZnAu ZnAu, Zn;Auzs, Zn,Au 
Cd-Cu Cd.Cu CdCus, Cd3Cus 








1 Zeit. f. Elektroch, 12, 726 (1906). 
2 R. Acc. Lincei, 28, IT. (1914); 24, I. (1915). 





PHYSICAL PROPERTIES. 81 


Thermo-electric Power. 


The study of the variation of thermo-electric power with 
the composition of an alloy has only recently been made in a 
systematic way by Ei. Rudolfi! and W. Haken.2 The 
researches of i. Becquerel? had led to the belief that the 
thermo-electric power of an alloy reaches its maximum 
when the components are present in equivalent proportions. 
The recent studies have shown this generalisation to be 
incomplete, but the fact noted by Becquerel served to call 
attention to this important field of study. 





fornce termoclottrrea a 
w& 











ae) Conceentranione 


BiG, 26; 


It is known that in a “ couple” of two metals the magni- 
tude of the electromotive force H depends on the temperature 
as well as the nature of the metals. In addition to the 
researches of Becquerel on the measure of / in alloys, the 
earlier work of Siebeck4 and C. L. Weber® should be 
mentioned. 


1 Zeit. anorg. Chem., 67, 65 (1910). 
2 Ann. d. Phys., (4), 32, 291 (1910). 
3 Ann. Chim. Phys., (4), 8, 408 (1866). 
4 Gilb. Ann., 73, 115, 480 (1823) ; Ann. Chim. Phys., 199 (1823). 
5 Wied. Ann., 28, 447 (1884). 
C.M. 6 


82 CHEMICAL COMBINATION AMONG METALS. 


Rudolfi studied the thermo-electric power of various 


alloys, as— 


1. Tin-cadmium. 6. 
9. Tin-zinc. oe 
3. Cadmium-zine. 8. 
4, Tin-lead. 9. 
5. Bismuth-cadmium. 1G: 


Lead-antimony. 
Gold-silver. 
Gold-copper. 
Nickel-copper. 
Platinum-palladium. 





Fora Bawirsoaletle CCE 














Cormnee irlrozLore 


Bigs 2%. 








¢ 





' 
' 
! 
! 
' 
| 
' 
| 
J 
| 
i 





> Congemt ADNLOMNL, 


EIG.-28 


PHYSICAL PROPERIIMS: 83 


He gives a general summary of the variations of thermo- 
electric power with the composition of alloys, laying down 
the following four types with accompanying diagrams. 

Typr 1. The two components mia wm the liquid state but 
solidify separately.—The curve of thermo-electric power 
assumes the form indicated in Fig. 26. It is a continuous 
line which can be calculated by the mixture rule. 

Typx 2. The two components form a serves of mixed crystals. 
—The curve here assumes the form of Fig. 27, showing a 
continuous variation passing through a minimum. 





1 
! 
' 
' 
' 
! 


cats ford hewpoe Clbrizg. 











’ 
; 





— +  Coneentrarione 
Fig. 29. 


T'ypE 3. The two components form a limited serves of mixed 
crystals —The curve (Fig. 28) shows that along B C mixed 
crystals separate while along 4 C conglomerates of mixed 
crystals together with the pure component separate. 

TypE 4. The two components form a compound.—The point 
C of Fig. 29 shows the composition of the compound. If 
solid solutions are formed in addition to the compound, the 
curve is modified according to cases 2 and 8, but this aspect 
of the problem is not yet well worked out. Haken (loc. cit.), 


who has studied the alloys of tellurium with antimony, tin, 
bismuth and lead, has succeeded in determining the limits of 
6—2 


84. CHEMICAL COMBINATION AMONG METALS. 


chemical combination in these alloys. He has further noted 
that for an alloy which shows a smaller electrical con- 
ductivity the thermo-electric force is greater. 


Thermal Conductivity. 


From the intimate relations existing between electrical 
and thermal conductivity—recently elucidated to a con- 
siderable extent by J. J. Thomson’s corpuscular theory— 
the laws regulating electrical conductivity may be expected 
to hold also for thermal conductivity. One well-defined 
relation is that the thermal conductivities of metals are 
nearly proportional to their electrical conductivities. This 
rule was demonstrated by the work of G. Wiedemann.t In 
the following table we give some values obtained by Wiede- 
mann for the copper-zinc and tin-bismuth alloys. The 
coefficient of thermal conductivity 1s given under «, that of 
electrical conductivity under X. 























Alloys. K r 
Ca-2n-— ratio 32-1 27°3 25°5 
3 Feed os eek 29-9 30:9 
. ees So ere | 31-1 29-2 
“ ee bead 25°8 25:7 
Sn-Bi ES 5 te | 10-1 9 
me ra tl 5:6 4-3 | 
i af ies 2°7 2 | 





The thermal conductivity « of certain binary alloys can 
be calculated according to F. A. Schulze? by the mixture 
rule; in the case of the bismuth-lead and bismuth-tin alloys, 
on the other hand, the value of « is less than that calculated 
by this rule. 

According to W. Voigt,? the determination of the ratio 

1 Pogg. Ann., 108, 393 (1859); Ann. Chim. Phys., (3), 58, 126 (1860) ; Phil. Mag., 
(4) 49, 243 (1860). 


2 F. A. Schulze, D.-A., 9, 555 (1902). 
3 Wied. Ann., 64, 95 (1898). 


PHYSICAL PROPERTIES. 85 


k:«, of the thermal conductivities of two substances in the 
case of heat flowing across the junction of two lamine may 
be given by x: x, = tan ¢,: tan ¢, where ¢, ¢, are the angles 
formed by the directions of heat flow in the two substances 
with the normal to their line of separation. 

The number of determinations made hitherto on the 
thermal conductivity of alloys is small. Among the most 
important researches bearing on the question of the occur- 
rence of intermetallic compounds are those recently made 
by A. EKucken and G. Gehlhoff,’ who have determined the 
conductivity of the cadmium-antimony alloys in which the 
compound CdSb (see Chapter V) occurs. They found that 
while for the metals the temperature coefficient of conduc- 
tivity has a value approximately 1-3, for the compound the 
value is about 2:8. It must, however, be borne in mind 
that the antimony-cadmium compound approximates in 
character to a metalloid, which renders it impossible to draw 
general conclusions from these results. At present this 
branch of the subject is comparatively little understood, and 
what knowledge we possess does not permit us to make any 
generalisations. The methods employed for the determina- 
tion of thermal conductivity are as various as the theoretical 
principles underlying them.? 

A physical constant of considerable importance 1s the ratio 
between the electrical conductivity \ and the thermal con- 
ductivity «x; it has been used, for example, in the study of the 
compound SbCd by Eucken and Gehlhoff (loc. cit.). This 
ratio, it can be argued, is influenced by temperature and 
increases proportionately to it. Some determinations of the 


cee 
ratio : between 600° and 0° have shown that it has an 


almost constant value for metals and is approximately 
1-367. The value becomes greater for alloys in which 
solid solutions or compounds occur. 


1 Ber., 14, 169 (1912). 
2 Cf. Chwolson, T'raité de Physique, Vol. IIL, pp. 348 et seg. Paris, 1909. 


86 CHEMICAL COMBINATION AMONG METALS. 


The temperature coefficient of thermal conductivity has 
been found to be positive for aluminium, gold and platinum 
and for certain binary and ternary alloys, such as manganin 
and constantin ; negative values are given by bismuth, tin, 
lead, cadmium, copper, silver, zinc, iron and nickel. 


Thermal Dilatation. 


The study of thermal dilatation has only been applied to a 
limited degree to metallic alloys. The investigations of 














Delewbors: CWA. 








Cu 





Fie. 30, 


Matthiessen ? and Le Chatelier ? have led to certain gen: rali- 
sations of value. 
For a solid isotropic body, length is in general a function 
of temperature and may be expressed by the formula :— 
P= Ase Be OR oe): 
where / and J, indicate the length of the body at # and 0° 
1 Pogg. Ann., 130, 50 (1867) ; Phil. Trans., 156, 861 (1866) ; Phil. Mag., (4), 31, 149 
(1866) ; 32, 472 (1866). 
 C. R., 108, 1096 (1889) ; 128, 1444 (1899) ; 129, 331 (1899). Cf. also by the same 


author : Sur les Propriétés des Alliages in the volume Contribution a ee des Alliages, 
p. 387. Paris, 1901. 


PHYSICAL PROPERTIES. 87 


respectively. A, B, C, etc., are constants. The coefficient 
of dilatation between 0° and ¢° is expressed by 
e=ALOB+ 8 Cr+... 

This coefficient has been principally used for the study of 
metallic alloys. Matthiessen, in the investigations mentioned, 
found that the dilatation of an alloy can be calculated by the 
mixture rule, for it is equal to the sum of the dilatations of 
its components. ‘This conclusion is, however, only valid in 
the cases in which the alloys are uniform conglomerate m1x- 
tures. Polymorphic transformations, for example, are always 
accompanied by discontinuities in the dilatation curves. 

A variation in the dilatation curve is to be attributed to 
the formation of solid solutions or of compounds. The 
presence of a compound, as Le Chatelier found, is indicated 
by the occurrence of a maximum in the dilatation curve. 
Le Chateher studied the dilatation of the copper-antimony 
and copper-aluminium alloys, in which the compounds 
SbCu,, SbCu,, AlCu, and Al,Cu appear. 

Comparing the fusion curve with the dilatation curve of the 
system CuAl, it is seen that at the first maximum in the one 
curve there corresponds a discontinuity in the other curve. 

The methods used for the determination of dilatometric 
data are various,! but will not be set out in the present 
volume. It may be mentioned that Tammann in col- 
laboration with Sahmen? has described a very accurate 
dilatometer. The investigations of Svedelius ? may also be 
mentioned. He has noted that in the cooling as well as in 
the heating of steel there occurs at about 660° and 730° an 
abnormal contraction which is connected with the carbon 
content of the metal. 

Guillaume * has also worked on the alloys of nickel. 


1 See Chwolson, T'raité de Physique, Vol. TIL, pp. 96 et seg., and Guillet, Etude 
Theorique des Alliages Métalliques, p. 147. Paris, 1904. Le Chatelier describes an 
optical method. Cf. Contrib. a 0 Htude des Alliages, p. 387. 

2 Ann. d. Phys., (4), 10, 879 (1903). 

8 Phil. Mag., (5), 48, 173 (1898). 

4. R., 124, 176, 752 (1897) ; 125, 235 (1897) : 186, 303, 356 (1903). Jour. de Phys, 
(3), 7, 264 (1898). 


88 CHEMICAL COMBINATION AMONG METALS. 


Hardness. 


Although it is difficult to give an exact scientific definition 
of the hardness of a body, it has come to mean the resistance 
which it opposes to a force acting on its surface. 

It has been found that the hardness of alloys 1s propor- 
tional to the composition when the constituents are present 
in the form of a conglomerate. The presence of solid solu- 
tions or definite compounds has, however, a considerable 
influence on the form of the hardness-composition curve. 
The most important investigations on this property m rela- 
tion to the composition of binary metallic alloys are those of 
Kurnakoff and his co-workers.’ Their studies have resulted 
in a rapid development of this method of investigation, 
which often furnishes reliable evidence as to the composition 
of alloys. 

Before describing the applications of the study of hard- 
ness to metallic alloys in which compounds occur, we 
may mention that this physical property has often 
claimed the attention of investigators. Thus, J. R. Ryd- 
berg” found that the hardness of elements is a periodic 
function of their atomic weights. He has given the 
values for all the elements in the order of Mendeléjeff’s 
classification. 

The values have been expressed by means of Moh’s scale 
of hardness, in which the following are the degrees :— 


de Dale: 6. Orthoclase. 
2. Gypsum. 7. Quartz. 
3. Cale-spar. 8. Topaz. 
4. luor-spar. 9. Corundum. 
5. Apatite. 10. Diamond. 


? Kurnakeff and Zemezuzny, Zeit. anorg. Chem., 60, 1 (1908); 64, 149 (1909) 
Kurnakoff and Pushin, ibid., 68, 123 (1910). Kurnakoff and Smirnoff, ibid., 12.31 
(1911). 

2 Zeit. phys. Chem., 38, 353 (1900). 


PHYSICAL PROPERTIES. 89 


HARDNESS OF THE HWLEMENTS (RYDBERG). 














| 
I: 1 Coe sli Pane! be LV: ve VI. VIL VIEL 
Li Be | B C N K 
6 (3) | 95 10 (-2) (+5) (-2) 
Na Mg Al Si P. | 8 Clie 
4 2 2-9 7 Bg (4) 
K Ca Si Ti V | Cr Mn | Fe Co Ni 
5 1-5 | (3) (4) (6) 9 (6) = 4:5 (5) (5) 
Cu Zn | Ga Gs AS Se Br 
3 2-5 | 15 (3) 35 |2 (-6) ; 
Rb Sr | x Zr Nb Mo Ru Rh Pd 
3 1-8 (3) (4) (6) (8-5) 6-5 (6) 4:8 
Ag Cd okra Sn Sb Te I 
2°]. 2 | 1-2 1-8 3 2°3 (-8) 
Cs Ba | La Ce Di 
2 2 (3) (Se 5) 
Ta | W Os. Ie Pt 
(7) (9) 7 6:5 4:3 
Au He Tl Pb i 
2-5 15 1-2 15 a | 


























‘I'he scale of hardness devised by F. Auerbach! is more 
rational and expresses the property in absolute degrees. 
Auerbach’s method is based on the following argument 
which had previously been elaborated by H. Hertz.’ If a 
convex surface of a body is compressed against a plane 
surface of the same body or another body a_ circular 
surface of contact will be produced, and the pressure upon 
this circular area eventually produces a rupture about its 
centre. As a measure of hardness, Auerbach takes the 
pressure P on the circle of contact (whose magnitude is 
determined microscopically) at the moment of rupture. If 
q be the area of the circle of contact and D its diameter, 

ee ee ed 
oa 2n(D)t a DY 
2 
P, varies inversely as the cube root of the radius of the com- 


1 Wied. Ann., 48, 60 (1891) ; 58, 380 (1896). 
2 Crelles Journal, 92, 156 (1882). Gesamte Werke, Vol. I., p. 155. 


90 CHEMICAL COMBINATION AMONG METALS. 


pressed sphere. The values obtamed by Auerbach for the 
fundamental substances on Moh’s scale are the following 
expressed as kilograms per square millimetre :— 


i ale 5. 6. Orthoclase 237. 
2. Gypsum 14. 7. Quartz 308. 
3. Calc-spar 92. 8. Topaz 525. 
4. Fluor-spar 110. 9. Corundum 1,150. 
5. Apatite 170. 10. Diamond eee 


According to Bottone + the hardness of metals is propor- 


tional to Where dis the density and m the atomic weight 


of the metal. KE. Benedicks,? in a later paper, in which the 
hardness of alloys and metals is studied from a general and 
theoretical point of view, examines Bottone’s results, from 
which, as shown, he deduces the formula— 

d 


D=kK-. 
m 


sat & ; 
The ratio : is called by Benedicks the atomic concentra- 


tion. In this property of solid bodies it is easy to trace an 
analogy with gases 3 for which according to Avogadro’s law 
the density is proportional to the atomic concentration at a 
given temperature. 


VARIATION OF HARDNESS WITH THE COMPOSITION OF ALLOYS. 


It has already been said that in binary alloys formed of 
simple conglomerates, the hardness varies almost always in a 
linear manner with the composition ; but, in practice, small 
deviations may be noted. Considering, however, that the 
observations are not always made under comparable con- 


1 Chem. News, 27, 215 (1878). 

2 Zeit. phys. Chem., 36, 529 (1901). 

5 Benedicks calls attention to this analogy, which is indeed not the only analogy 
existing between different states of matter. 


PHYSICAL PROPERTIES. 91 


ditions and that the mode of preparation of an alloy has an 
influence on its hardness, such deviations do not greatly 
invalidate the general conclusion. Fig. 31 shows the form 
of the hardness curve where the alloys are composed of 
simple conglomerates. The hardness varies in a linear 
fashion between the pure components A and 6, whose 
hardness is represented by A’ and B’. 

The case is different where alloys are constituted of 
isomorphous mixtures (solid solutions) or contain one or 





> ———=>> Durcrra 











A SS Coneenlriayione B 
Fiqg, 31. 


more definite compounds. The investigations of Kurnakoff 
already noted have not only embraced such cases but also 
cases in which a compound forms solid solutions with the 
components. 

Kurnakoff’s first rule for the hardness of isomorphous 
mixtures is that the property increases so as to reach a 
maximum for the median composition of the series of mixed 
crystals. This is shown in Fig. 82. 

Tammann? has given a rational explanation of this 


1 Of. Tammann, Ueber die Beziehungen zwischen den inneren Kraflen und Eigensch. 
der Losungen, p. 35 (1907) ; also Lehrb. d. Metallographie, p. 332. 


92 CHEMICAL COMBINATION AMONG METALS. 


behaviour. He supposes that in a given mixture the forces 
of attraction between dissimilar molecules are greater than 





> —» Durere 











A —3 Concemliarviowe 


HG 32: 
those between similar molecules. From this it follows that 


for liquids, the internal pressure, resulting from the sum of 
the forces of attraction per unit surface, is increased by the 














cf 

° c 
g ; 
—) ’ 
} 

! é 
A : 
| 

A Aaba B 


— Concerlratione 


Fig. 33. 


PHYSICAL PROPERTIES. 93 


addition of another substance, and this must be the case 
with alloys. According to Tammann the attraction of two 
dissimilar molecules is greater both in the isotropic and in the 
anisotropic state. 

When the formation of a compound takes place between 
two metals, the hardness increases and the maximum corre- 
sponds to the composition of the compound. The curve 
representing this behaviour consists therefore of two 
straight lines starting from points representing the hard- 
ness of the components and intersecting In a maximum point 
(Fig. 33). 

The following table, giving the hardness of various inter- 
metallic compounds, illustrates this pomt. The values for 
the pure components are also given. Hardness is given in 
degrees on Moh’s scale. 














Hardness of 
Compounds. 
Compound. Components. 

Mg,Sn 3°5 Mg —- 2 so) Coat a 
Mg,Pb oro Pe Pb — 155 
MgCu, 4-5 = Cu — 3 
Mg,Cu AeD : 
Zn,Cu Ae5 Zn — 2 re 
Cu,Sn 45 Sn — 1°8 % 
Cu,P 6 + P — 55 us 
Cu,Sb 4:5 Sb — 3 - 
CdSb 3°5 3 Cd — 2 
CoSb Do ie Co — 4+ 
NiSb 5 — 55 3 Dre. 
CoSn 55 Sn — 18 Co — 4+ 
CoSn, DO 9 29 
PbSb, 5d Sb — 3 Pb — 1°5 
Ni; As, 6°5 Ni —4. + AS — 3-9 
Ni;P, BOF ie P —°5 
PtSn Bep Pt — 4:3 Sn — 1:8 
NaCd, Feo Na —: 4 Cd —.2 
Na,Pb 2-5 = Pb -- 1°5 
NaPb 3 + Ss = 
NaSn 3+ s Sn -- 1:8 














94 CHEMICAL COMBINATION AMONG METALS. 


When a compound forms solid solutions with the com- 
ponents, the hardness curve differs from the preceding cases 
described. Here two maxima appear and a point of inter- 
section. ‘The maxima correspond to the formation of mixed 
erystals and the point of intersection of the two branches to 
the compound (see Fig. 34). Kurnakoff and Smirnoff! 
have classified the hardness curves for alloys in which, in 
addition to the compound, solid solutions are formed. We 





Dea sire: 








I 
' 
i 
| 
{ 








Pas AmBn B 


= Orient iaaonks 


Fig. 34, 


have discussed the question of compounds of variable 
composition in Chapter III. Kurnakoff and Smirnoff 
divide the cases in question into two groups: (1) com- 
pounds which are not dissociated either in the liquid or 
the solid state; and (2) compounds which dissociate on 
fusion. We will examine more closely the significance of 
this classification. 

Group 1.—These compounds belong to the category of 
hylotropic phases mentioned by Ostwald.? ‘Two types are 


1 Zeit. anorg. Chem., 72, 31 (1911). 
2 Zeit. f. Elektrochemie, 10, 572 (1904). 


PHYSICAL PROPERTIES. 95 


distinguished ; in the first, (a), the compound forms a con- 
tinuous series of solid solutions with the components ; in the 





e 





D cagromm*na & fu Seon 





WY yy Yyy | 
Y$us Y/// Wf 


Durere CX 





































































































Diagram ntm S. furs corre 





























D> ayers: TN. 
e 
\ 
xX 











A Am Bn : vo) 


96 CHEMICAL COMBINATION AMONG METALS. 


second, (b), the compound forms solid solutions only to a 
limited extent. 

Types (a).—This case is shown in Fig. 35, where ¢ repre- 
sents the melting point of the binary compound 4,, B,. 








WesZOUT UOIsng 











SSaupJOH 
\ 
x 
4 
J 
! 
/ 
‘ 
I 














Composition 
< Fig. 37, 
This may be between that of the two components, as in the 
diagram, or even above or belowthem. The two systems of 
isomorphous mixtures A + A, B, and A, B, + B are 
represented by the two curves a, df and f eb, with maximum 
points ind ande. The minimum f corresponds to the com- 


PHYSICAL PROPERTIES. 97 


pound 4,, B, ; this may be found also above a, and b,, i.e., 
the hardness of the compound 4,, B, may exceed that of the 
components. 

Typx (b).—As was said, this type is characterised by a gap 
in the series of solid solutions. The compound (see Fig. 36) 
shows a maximum and forms solid solutions with excess of 
A and B in the region limited by the lines e, ¢, g d, f,. The 
curve | f n represents the variations of hardness in the 
interval of concentration e, f,. The presence of solid 
solutions is accompanied by an increase in hardness and 
the two branches intersect in J; which represents the com- 
pound. 

Group 2.—The behaviour of substances of this group is 
represented by Fig. 837. The compound melts at the point 
D and gives rise to the component B.D, which is the point 
of intersection of the horizontal D D, with the curve C, M 
(which indicates the concentration of the solid solutions) 
represents the highest temperature at which the solid phase 
of the compound is stable. The branches D M Kk and 
D, M ky, which pass through the obscured maximum | M ; 
polene to the labile state of the compound. 

Discontinuities occur at P and Q corresponding to changes 
in the hardness of the solid solutions with A and B. 

The measurements of hardness made up to the present 
have been carried out either by means of the sclerometer or 
by Brinell’s method. 


Compressibility. 

In direct relation with the hardness of a substance is the 
property of compressibility under pressure. Kurnakoff has 
used this property also in his investigations on the variation 
of the physical properties of alloys with their composition 
(see Bibliography, p. 88). Since this property is intimately 
connected with hardness there is no purpose in giving any 
particular detailed treatment of the subject. It is sufficient 


to mention that in isomorphous mixtures the compressibility 
c.M. 7 


98 CHEMICAL COMBINATION AMONG METALS. 


as well as the hardness, exhibits a maximum on the curve 
showing its relation to composition. The apparatus used by 
Kurnakoff is described in the first memoir,! and has been 
used for conglomerates of mixed crystals, metals, inorganic 
salts and organic substances. Among the substances thus 
examined are the thallium-lead and thallium-bismuth alloys, 
binary mixtures of silver chloride and bromide, potassium 
iodide and bromide, stearic and palmitic acids, p-dichloro- 
benzene and p-dibromobenzene. 

The researches of Kurnakoff on the compressibility of the 
thallium-bismuth alloys are above all worthy of note since 
they have served in the determination of the irrational 
maximum of the compound of variable composition whose 
formula is approximately Bi;Tl, (see Chapter V). 


Crystalline Form of Binary Compounds, 


Comparatively few intermetallic compounds have been 
studied crystallographically, so that we possess very little 
definite information on this subject. Studies are also want- 
ing on the relations between crystalline form and degree of 
saturation of compounds. 

The crystalline forms of metals are generally known ; 
they crystallise most often in the regular or the hexagonal- 
rhombohedral systems. Silver, cadmium, iron, iridium, 
mercury, nickel, gold, osmium, lead, platinum, palladium 
and others of the platinum group belong to the regular 
system. The latter are, however, dimorphous and crystallise 
also in the hexagonal system. Arsenic, beryllium, antimony, 
bismuth, magnesium, tellurium and zine crystallise in the 
hexagonal system. Potassium and sodium are tetragonal, 
while tin crystallises in the tetragonal and also in the 
rhombohedral system. Zirconium is monoclinic. The inter- 
metallic compounds given in the following table have been 
studied crystallographically :— 


1 Zeit. anorg. Chem., 60, 22 (1908). 


PHYSICAL PROPER EIES: 218) 




















| 

Compound en Compound. tae 

| | | 

| NaCd. Cubic | FeZn, Hexagonal 
Mg.Sn ‘ | NiAs (Niccolite) - 
Ag.Te i NiSb fe 
Ag,Zn : | BjeTe; (Tetradimite) ie 
AgoZn = | NisTe; (Melanite) _ 
AgZn ip | Cd3Sbe Orthorhombie 
Cu,Ni Fe | FeSbe a 
CueZn . _ AgeSb (Dyscrasite) be 
CuZn . | ZnSb ie 
CuZns » + | FeAg, (Léllingite) . 
PbTe (Altaite) i _ NiAse (Rammelsbergite) * 
CoAs, (Smaltite) ae | CoAse (Safflorite) g 
NiAg, (Cloantite) ae | CeAl, 
CoAs, me LaAl, a 
PbAxg, (Sperrilite) re | Thal, oe 
CuSne Hexagonal | FeAl, Monoclinic 
CuSn ne | AsSng Tetragonal 
Cu,Sn * | 








Our information on other intermetallic compounds is 
very limited. Groth, in his Chemische Krystallographie,! 
gives certain data about artificially prepared compounds, 
whose crystallographic characters are not yet well under- 
stood. ; 

(a) Bivalent Metals—The compounds of beryllium and 
magnesium with monovalent metals have not yet been 
studied crystallographically. 

The zinc compounds with copper and silver described by 
Behrens ? have been given in the above table. The amal- 
gams of lithium, sodium and potassium are very numerous ; 
they crystallise partly in needles and partly in hexahedral 
forms. Some of the copper, silver and gold amalgams 
crystallise in the cubic system. The compound CoHg, was 
obtained in prisms which, however, were not examined very 
exactly. Crystalline amalgams exist of barium and 
strontium. 

1 Vol. IL. pp. 43 ef seg., 1906. 

2 Gefiige d. Metalle u. Legierungen, pp. 46 and 100. Hamburg and Leipzig, 


1894. 
7-—2 


100 CHEMICAL COMBINATION AMONG METALS. 


(b) Trwalent Metals —Behrens ! and Guillet ? obtained the 
following crystalline compounds of copper and aluminium : 
Cu,Al, CuAl and Cu,Al, ; Petrenko * obtained two crystalline 
compounds of aluminium and silver, namely, Ag,Al and 
Ag ,Al; Heycock and Neville* prepared from aluminium 
and gold, Au,Al, Au,Aland AuAl, ; but the crystalline form 
of all these compounds was not determined. 

Thallium forms compounds with the monovalent metals in 
which it behaves as a heavy metal. Jurnakoff,° from the 
thallium-sodium and thallium-potassium alloys, obtained 
the compounds NaTl and KT, the former in the form of 
three-rayed aggregates and the latter in the form of cubes. 
The thallides of the bivalent metals, of which some of 
magnesium are known, are very little recognised. 

(c) Tetravalent Metals. — In addition to the stannides 
shown in the preceding table, Groth® refers to the com- 
pound Cu,Sn which crystallises in small prisms. The 
compound CuSn, was described by Miller * and Ram- 
melsberg ® as occurring in hexagonal prisms. The stan- 
nides of silver have not yet been isolated nor have the 
compounds with gold, AuSn, AuSn, and AuSn, described 
by Vogel.’ 

Copper and silver form double pluwmbides: Curlt 
describes the compound CuAgPb, as forming regular 
octahedra. The gold plumbides described by Vogel,” 
Au,Pb and AuP, crystallise respectively as rhombs and long 
needles. 

Among the stannides of iron, Fe,Sn, Fe,Sn, FeSn and 


1 Op. cit., p. 107. 

2 Cc. R., 133, 684 (1901). 

3 Zeit. anorg. Chem., 46, 49 (1905). 

4 Trans. Roy. Soc., 194, 201 (1900). 

5 Zeit. anorg. Chem., 30, 86 (1902). 

Op. cil. p. AG. 

7 Phil. Maq., 1835, p. 107, and Pogg. Ann., 86, 478. 
8 Zeit. anorg. Chem., 46, 60 (1905). 

9 Pogg. Ann., 120, 34 (1863). 

10 Uebers. d. pyrogen. Kunstl. Mineralien, Freiberg (1857), p. 17. 
11 Zeit. anorg. Chem., 45 (1905). 


PHYSICAL PROPERTIES: 101 


FeSn,, described by Headden and Stevanovitch,! are known. 
The bistannide crystallises in long needles. 

Few stannides of the trivalent metals are known: the 
stannides of aluminium, AlSn, and AlSn, prepared by 
Guillet? have not been studied crystallographically. 

It is worth while recording here the observations of 
Barlow and Pope’ on a regularity in the crystalline form of 
binary compounds formed by the union of elements of equal 
valency ; such compounds crystallise in the cubic or 
hexagonal systems and generally in classes with a lesser 
degree of symmetry. According to these authors, the mole- 
cules which form the homogeneous structure which is the 
crystal are constituted of similar atoms. But beyond this 
similarity of the atoms it is possible to think of other factors 
which influence crystalline form. The homogeneity or 
uniform structure of the crystal is conditioned by two oppos- 
ing forces: (a) a repulsive force due to the kinetic energy 
of the atom, and (b) an attractive force varying as the square 
of the distance between the atoms. | 

Concerning this question of the nature of the forces which 
maintain the component atoms of crystals in equilibrium, 
Nernst and Lindemann* have recently stated that the 
attractive force is identical with that of chemical affinity. 
This, of course, throws additional light on the regularity 
noted by Barlow and Pope. 


Natural Intermetallic Compounds. 


Among the intermetallic compounds studied, the majority 
are homopolar, resulting from the action of unitary forces. 
Compounds of this group are not ionisable and exhibit in 
their properties the properties of their constituent elements. 
All intermetallic compounds, however, are not formed by 


1 Zeit. f. Krystall, 40, 327 (1905). 

2 0. R., 133, 935 (1901). 

3 Trans. Chem. Soc., 89, 1675 (1906). 

4 Of. Nernst, The Theory of the Solid State, p. 4, London, 1914. 


102 CHEMICAL COMBINATION AMONG METALS. 


the union of homopolar elements. Indeed, certain metal- 
loidal elements are able to form with metals true alloys having 
markedly metallic characters. Among such metalloidal 
elements are carbon, silicon, boron, tellurium, selenium, 
phosphorus and arsenic. 

The natural intermetallic compounds are generally hetero- 
polar. Native metals are few in number and chiefly alloys 
of the elements of the iron group (iron, cobalt and nickel) and 
of platmum, mercury, copper, silver and gold. Among 
these metals those with the highest melting points tend to 
form solid solutions. Thus gold forms solid solutions with 
silver (electrum), palladium and rhodium, osmium and 
iridium from iridosmin ; and lastly, in meteorites, nickel and 
iron are found united in solid solutions. 

The following tellurides occur naturally :— 


AgTe — Silvanite and em- | AgAuT'e, — Krennerite. 
pressite. AgAuTe — Muthmannite. 

Ag, Te — Hessite. HgAu,Ag,Te — Kalgoartite. 
Ag, Te — Stutzite. bi, Te, — Tetradimite. 
AuTe, — Colaverite. HeTe — Coloradoite. 
(AgAu), — Petzite. PbTe — Altaite. 
(AgAu),Te, — Goldschmite. | NiT’e — Melanite. 





Silvanite, colaverite and krennerite, though recognised as 
definite minerals have not been encountered in the study of 
fusion diagrams. Pellini! has found recently in the study 
of the system silver-gold-tellurium by thermal analysis the 
compound (AgAu),Te,, which has not been discovered among 
the gold minerals hitherto investigated. mpressite was 
found recently by M. W. Bradley ?; Pellini and Quercigh 3 
have also noted the existence of the compound AgTe by 
thermal methods. 

Stutzite is probably a mixture of Ag,Te and silver, while 
melanite probably contains the compound NiTe. 

1 Gazz. Chim. Ital., 45, I., 47 (1915). 


2 Journ. of Science, 38, 163 (1914). 
3 RK. Acc. Lincei, 19, IL., 415, 445 (1910). 


PHYSICAL PROPERTIES. 103 


A bismuth telluride must also be mentioned whose com- 
position is not exactly known and which has been called 
Joseite. 

The following native antimonides and arsenides occur :— 


Ag,sb — Dyscrasite. ek Loélhnegite. 

Ag sb — (variety of dyscra- ; ee 
site). Fe,As, — Lemopyrite. 

Cu,Sb — Horsfordite. eit (Smaltite. 

NiSb — Breithaufite. "2 | Safflorite. 

Ag As — Arsenoargentite. CoAs, — Skutterodite. 

Cu,As — Domeichite. NiAs — Niccolite. 

Cu,As — Algodonite. Nike Caras 

Cu,As — Whitnegite. 2| Rammelsbergite. 


PbAs, — Sperrylite. 
Co(AsBi), — Bismuthosmal- 
tite. 





A selenide of bismuth, guanajnatite, exists of the com- 
position Bi,Se,; silvanite, to which at first the formula 
Bi,Se was assigned,! has been since? recognised to be a 
mixture of Bi,Se, and bismuth. N. Parravano,? in a study 
of the system B:—Se, has demonstrated the existence of 
two selenides, Bi,Se,; and BiSe. 

The mineral naumannite, Ag,Se, found in nature, is 
isomorphous with argentite and hessite. Naumannite and 
hessite are found in isomorphous mixtures in the mineral 
aguilarite. The system silver-selenium has recently been 
studied by Pellini.* 

Some of the minerals here mentioned and at present 
regarded as definite compounds are probably isomorphous 
mixtures. Although a mineral may have a uniform 
structure and a constant composition it is not always a 
true chemical individual. In this connection it is well to 
bear in mind that several native compounds have not been 





1 Zeit. f. Kryst., 1, 499 (1877). 

2 Thid., 6, 96 (1888). 

3 Gazz. Chim. Ital., 43, I., 201 (1913). 
4 Ibid., 45, 1., 533 (1915). 


104 CHEMICAL COMBINATION AMONG METALS. 


recorded in the thermal study of the mixtures of their 
constituent elements. 

The recent developments of the study of heterogeneous 
equilibria and the introduction of Tammann’s method into 
physico-chemical research, although they have not led to a 
complete elucidation of this important aspect of mineralogy, 
have nevertheless furnished powerful means of investigation 
which promise much for the future. 


CEA Vii. Vo 
Homopotar INTERMETALLIC COMPOUNDS. 


Compounds of the Elements of Group I. among 
themselves. 


1st sub-group.—The only compound known in this sub- 
eroup is that formed by sodium with potassium. The 
sodvum-potassvum compound has the formula Na,K. The 
system has been studied by Kurnakoff and Pushin ! and the 
diagram is shown in Fig. 38. According to Kurnakoff the 
curve shows a break corresponding to 40 per cent. of 
potassium at 638°; this may demonstrate the existence of a 
compound of the formula Na,kK or Na,K,.  Bornemann 2 
on the other hand believes that there are three species of 
mixed crystals between the two pure components. The 
branches of the curve Na a and Ky are convex to the axis 
representing concentration, showing that the two metals 
instead of separating in the pure state form solid solutions. 
According to Bornemann the presence of a strongly dis- 
sociated compound of the type Na,K must be admitted. If 
we hold with Kurnakoff that the break on the fusion curve 
corresponds to the compound, so that the crystals B 
saturated with sodium are identical with the compound, we 
may have Na,k or Na,K. The composition represented by 
Na,Kk is near a point of arrest. Bornemann holds that it 
should be characterised by a more decided point of arrest 
and that the compound is probably Na,Kk.? 

Lithium is miscible with sodium and potassium with 


1 Zeit. anorg. Chem., 30, 109 (1902). 
2 Die binaren Metallegierungen, Halle (1905), p. 7. 
3 Cf. also Van Bleiswyk, Zeit. anorg. Chem., 74, 152 (1912). 


106 CHEMICAL COMBINATION AMONG METALS. 


difficulty.t Nothing is known of the behaviour of lithium 
and sodium with cesium and rubidium. 
2nd sub-group.—Copper, silver, and gold give alloys with 





90° 





80° 


60" VA | 
4 nN 1 
4 fy 
ey 7 : 
gui 
40° vo Z | 
30° 


20° is) ip N 













































































7 iS 
\ 
40° Gn 4 NY 
oe A & YY 
co is ) a font : XC 
! {> N \S 
\ | 
2s0° ! | GON L x WN 
| SZCZRINISSSSE SS 
: | | ! | 
bf ee (aa ee eer rT oe bases “G0 700 


each other with complete or partial formation of solid solu- 
tions. Sodium alone among the elements of the first sub- 
group forms the compound NaAu,. The system sodvwm- 


1 Zeit. anorg. Chem., 67, 183 (1910). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 107 


gold has been studied by Mathewson, who has noted the 
formation of a compound. Silver and copper on the con- 
trary do not combine with sodium, which, of course, is 
contrary to Tammann’s rule. 

The diagram (see Fig. 39) is fairly simple. At a concen- 










































































{ "eq A (ve Q 
re) oul = = 
4S aan = co 
ERD IED CY SRC ~ A eyo We Se 
900 CSS Seal el HE IE ay OD 
goo aia aaron nee ae 
——— 1 
hoa ee Sees aaa 
(B= eee ees 
/ aaa pe oer ies Care 
600 et 
— HS 
00 ——— 
oe 




































































O- 49 4o 50° ~-i5-O- - $0 60 TO." 80 90 100 
> Do Oboe Au 





Fia@, 39. 


tration of 8-6 per cent. of gold there is an eutectic point ; at 
66-6 per cent. of gold and at 989° there is a maximum corre- 
sponding to the compound NaAu,. A second eutectic 
between the compound and gold occurs at 876°. There 
is no indication of the formation of solid solutions in 
the diagram. The compound NaAu, is chemically very 
resistant and exhibits a considerable degree of hardness. 


1 Intern. Zeit. f. Metall , 1, 85 (1911). 


108 CHEMICAL COMBINATION AMONG METALS. 


Compounds of Elements of Group II. with each other. 


1st sub-group.—The behaviour of the metals of this sub- 
group has not been studied as yet. 

Ind sub-group.—Magnesium forms with zinc the compound 
MeZn,; with cadmium it forms the compound MeCd, and 
with mercury a compound whose composition is not yet 
determined. 































































































700° 5 
Mg Zn, 
50 | nee 
600° 
ta 
ey 
0c WY a os 
Ugo 
50 Vii PY SPs: : 
50 Sg ae : 
300° 7 | 
0 0 1400 


10 20 ~=6- 0 40 0 360 tor 30 9 
Z . 2 ut Clonn Aba 





Fia. 40. 


Magnesium-zinc.—The system magnesium-zine has been 
investigated by Boudouard! and Grube.2 From the 
diagram constructed by the !atter, who has traced cooling 
curves from 650° to 250° (see Fig. 40), Grube inferred the 
existence of a compound MgZn,, which is formed at 590°, 
and at 83 per cent. magnesium. A small deviation noted 


1 OQ. R., 189, 424 (1904). Bull. Soc. Chim., (3), 31, 1201. 
2 Zeit. anorg. Chem., 49, 77 (1906). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 109 


near the eutectic point between magnesium and MgZn, is due 
to the presence of magnesium or the compound, which must 
be attributed to super-cooling. Grube denies the formation 
of solid solutions on the one hand between the compound 
and magnesium, and on the other hand between zinc and the 
compound. Magnesium tends on first separation, 1f present 
in small quantity, to crystallise in dendritic forms. Accord- 
ing to Boudouard the compound Mg,Zn is also formed. 
This, however, is denied by Grube, arguing from the theory 
of heterogeneous systems, since the eutectic horizontals of 


700° 
600° CaMs K 
500° | AS : 


| sss RB 
400° aaa 








Oo 















































‘6 10 1a 90 40 50 GO 20 Q {00 


8O 9 
Sone cane, WE Clon Mg 
Fie. 41. 


the compound MgZn, extend over the whole diagram. 
Microscopic analysis also excludes the formation of Bou- 
douard’s supposed compound. 

The compound MgZn, is unattacked by water and air ; it 
has a brilliant white colour and is a little harder than its 
constituents. It is very brittle. 

Magnesvum-cadmium.—The system magnesium-cadmium 
has been investigated by Boudouard ! and Grube.? Accord- 
ing to Boudouard the compounds MeCd, Mg,Cd and Mg,Cd 
occur, while Grube only reports one compound, namely, 
MgCd. From the diagram (Fig. 41) he argues complete 
miscibility both in the liquid and solid states. 


1C. R., 184, 1431 (1902). Bull. Soc. Chim., (3), 27, 854 (1902). 
2 Zeit. anorg. Chem., 49, 72 (1906). 


110 CHEMICAL COMBINATION AMONG METALS. 


Near 50 per cent. of cadmium the crystallisation interval 
between liquid and solid practically vanishes so that the 
liquidus and solidus curves touch. 

Between 35-9 per cent. and 66-4 per cent. of magnesium 
the compound MgCd and the mixed crystals of the compound 
and its components undergo a transformation into another 
series of mixed crystals. By crystallising slowly, homo- 
geneous alloys are obtained. 








ee ES RS 
pa QA 
































3A - 
2 nk Saha 
— 
4100 Se 


I 
i 


re <= 
fa 
es ey 1 
A 
| 
a5 





















































0) x = 
ae, SS ee 
-~50 qe 
2100U2= 








Die OE i AO OS OO Sra BO he 
Se SEO teat 


Fie, 42. 
The compound MgCd is greyish-white in colour, a little 


harder than its constituents, and very resistant to water and 
moist air. 


MAGNESIUM AND CALCIUM AMALGAMS. 


Mercury-magnesium.—This system has recently been 
studied by L. Cambi and G. Speroni.!_ The two elements 
combine to form the compounds MgHg, and MgHg. The 
system has been investigated up to a concentration of 50 per 


1 R. Acc. Lincei, 24, I., 734) 932 (1915). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 111 


cent. magnesium. Preliminary researches were made by 
Wanklin and Chapman’ and by Kerp and Bottger.? 

By addition of a very small quantity of magnesium the 
melting point of mercury is lowered (see Fig. 42). The 
diagram then rises in a curve to 168°, where there is a dis- 
continuity corresponding to the compound MgHg,. The 
existence of the compound MgHg has not been proved 
directly by the thermal method, for this series of observations 





LOOr 


















































; | 
" ZEEE 
A 7) Ca 
Sg BEA 
Bog Zs Seige s 
Tt ee es’ 
( (ees ™ 
~ r 
ae 2 
Yoo sa 
ae 
oe eee 
So ee ; 
Baur pe eee 
le wl te 
jet 
— ia! 
50 2 we 
TORT pee Ea Se 
a r 
0 << 
aes 
SESE pee Ma OS 
50 | | ae aia 
al % \ i | 
too 





























\ 
©) ei A | alee Sara Eee 8 ea 
em Ct: Ca 


Pre, 43. 


terminates at 5-08 per cent. by weight or 30 per cent. atomic 
of mercury. The amalgam with 32—34 per cent. atomic 
magnesium boils at 415°. Cambi has also studied the elec- 
tromotive force of magnesium amalgams. 

In 1904 Evans and Fetsch,? working on magnesium amal- 
gam as a reducing agent, prepared a homogeneous amalgam 
corresponding to the formula MgHg, from one part mag- 
nesium and eighteen parts of mercury. The formation of 

1 J.C. S., (2), 4, 141 (1866). 


2 Zeit. anorg. Chem., 25, 33 (1900). 
3 J. Am. C, S., 26, 1158 (1904). 


112 CHEMICAL COMBINATION AMONG METALS. 


this compound is shown clearly by the thermal study of the 
system. 

Mercury-calcvum.—tThe affinity of calctum for mercury is 
very slight; at ordimary temperatures calcium dissolves 
slowly in mercury. The capacity for combination between 
the two metals has long been known, but the system has only 
been studied recently by Cambi and Speroni! who have 

shown the existence of the compound CaHg,. 
~The diagram is shown in Fig. 48 and only extends to 83 per 
cent. atomic of calcium. The compound melts with decom- 
position at 266°C. Thermal analyses do not indicate the 
existence of any other compounds. Moissan and Chavanne 2 
had previously described a compound of the formula CaHg, 
crystallismg in hexagonal prisms. J. Schiirger ? recorded 
the existence of a crystalline compound CaHg, while 
J. Ferée* described a compound Ca,Hg, easily altered on 
exposure to air. Thermal analysis, however, renders the 
existence of the last three compounds very improbable. 

Strontuum-mercury.—sStrontium like the other metals of 
the alkaline earths combines chemically with mercury. 
From the researches of Kerp and Béttger ° the existence of 
the compound SrHgjo, in equilibrium with the liquid phase 
at 80°, appears established. It decomposes at 60° to 70° 
and has a silvery appearance. An amalgam of strontium 
containing 5:37 per cent. of this metal separates a crystalline 
phase at 81°. ‘The system has not yet been investigated by 
thermal methods. 

Barvum-mercury.—Barium combines with mercury. Kerp 
and Kerp and Béttger ’ isolated two amalgams of the com- 
position BaHg,, and BaHg,, by electrolysis of a saturated 
solution of barium chloride, using a mercury cathode. 


6 


1 R. Acc. Lincei, 28, II., 599 (1914). 
2-0. R., 140, 125 (1905). 

3 Zeit. anorg. Chem., 25, 426 (1900). 
4 C. R., 127, 619 (1898). 

5 Zeit. anorg. Chem., 25, 1 (1900). 

8 Thid., 17, 284 (1898). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 113 


BaHg,, crystallises in silvery cubes which become oxidised 
in the air. The amalgam containing 5:34 per cent. of 
barium separates a crystalline phase at 99°. 

The system has not yet been studied thermally. 


COMPOUNDS oF CALCIUM witH METALS OF THE SECOND 
SUB-GROUP. 


Calcvum-magnesvum.—Calcium combines with magnesium, 
forming the compound Ca,Mg,. The system has been 





1009 

































































§00 
foo Me. 25 
100 = me SNP \ 
Dees oe 
soo Lil MESES SS SWI AS 
Ge a SS 
t = ae: ig 
400 4 &: | tp Z 
: ! 
300 ! - 
! 
too : 
ee) foe eee ere: oe Fe ae geo 798) 


Se ee pare Cas, 


Fig. 44, 


worked out by Baar. The diagram traced by him (Fig. 44) 
shows that in the liquid state magnesium mixes with calcium 
inall proportions. The liquidus curve shows a maximum at 
55 per cent. (by weight) of calcium and 715°. Here the 
compound Ca,;Me, separates. Microscopic examination 
confirms the deductions made from the diagram, and 
shows that the compound exists in polyhedric crystals. 
The magnesium-calcium alloys, particularly those found 
in the vicinity of the composition of the compound, are 


1 Zeit. anorg. Chem., 70, 362 (1911). 
C.M. 8 


114 CHEMICAL COMBINATION AMONG METALS. 


very brittle; the alloys richer in calcium are more ductile. 
Exposed to air these alloys crumble to a grey powder in 
which are seen shining particles of the compound which 1s 
stable in air. 

Calcitum-zinc.—This system was studied by Donski,! who 





800° ‘c L465 
| “a CGILA Ga Zn, 
T 


50 





C4 Zn 


IN 





700° 








50 














( aid 
SA 
Linon 











600° 


50 








500° 


eae, SQ 


OC MAUL Atay N 


50 







































































SS LEM is SAN 
*. y eee i oH Q bee is 
+00 : Cain == €a 
Ca, Zn, Reba ey om Ti eG ea 
Zn a Ca Zn Ca, Zn 
50 ; 
a Ca Zn’ ie 
Ca Zn, Ca, Zn Ca 
ga: 10 20 30 LO 50 GOe tO 80. POs = ACO 
——_ > wee aA ow 
Fig. 45. 


noted the formation of four compounds, namely, CaZn,p, 
CaZn,4,CaZng, and Ca,Zn. On the fusion curve (see Fig. 45) 
between 9 and 20 per cent. Ca, there are distinct breaks at 
677° and 717°. The compound CaZn, separates from its 
melt and from melts containing large proportions of it only 


1 Zeit. anorg. Chem., 57, 185 (1908). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 115 


after a super-cooling of about 16°. The second compound 
crystallises at 680° from melts containing 9-238 per cent. of 
calcium. This compound either melts without decomposi- 
tion or else in melting splits off a small quantity of the com- 
pound CaZn,). The first case occurs if the composition 
coincides with a point of transition, the second case when the 
composition is represented by points lying to the left of the 
said point. The curve rises again up to 40 per cent. calcium 
at a temperature of 688°, where the compound Ca,Zn, 
separates. In the further course of the curve small arrests 
are noted at 431°, which probably correspond to a compound 
CaZn. Other arrests occur at 385°, between 52 and 84 per 
cent. of calctum with a maximal arrest at 80° calcium. This 
means that another species of crystal is formed having the 
formula Ca,Zn. 

The alloys from 0—6 per cent. calctum have the colour of 
pure zine and are a little harder ; they are fairly stable in air, 
while those containing from 6—19 per cent. of calcium soon 
become grey. From 20—29 per cent. they decompose water, 
giving a black powder, and with greater energy the richer 
they are in calcium. The brittleness of these alloys increases 
from pure zinc up to 80 per cent. of calcium, diminishing 
thence as the proportion of the latter metal increases. 

Calctum-cadmium.—Calecium combines with cadmium, 
forming the three compounds CaCd;, CaCd and Ca,Cd,, 
according to Donski.t The curve (ig. 46) shows a break at 
615° and 24 per cent. of calcium and an eutectic point at 316°. 
The compound CaCd, separates only after a super-cooling of 
about 8°. At 685° from 27 to 84 per cent. of calcium, a lack 
of miscibility in the liquid state is noted. The compound 
CaCd forms at 50 per cent. of calcium, and arrests are 
observed corresponding toit. At about 515°, a new species of 
crystal separates which may be the compound of the formula 
Ca,Cd,, but this is not quite certain since the eutectic 
horizontal extends to 50 per cent. of calcium, whereas it 


1 Zeit. anorg. Chem., 57, 193 (1908). 
8—z2 


116 CHEMICAL COMBINATION AMONG METALS. 


should extend only to 40 per cent. The last arrests are 
at 415° from 50—95 per cent. calcium, and correspond 
probably to mixed crystals. 

The alloys containing up to 10 per cent. of calcium are 
fairly stable in the air and a little harder than calcium ; from 





750° 
/ Ciuc Cea \ 


: cay 


700° 


\ 
{ Aidiza _\ 
60 RSsss— at as S 
BSS 
AZ bee 
eee A 


CLaL08 ened 
NCL AZZGIS 








o 




















50 


























ga 
Fee \N 
WAZ, 








oC 





/ 

50 
[S 
400° ac 
s 
SN 





Ca 





















































300 oe = 
Cc 
Catt Ca Cd, 
250° 4 
Oo Yo L6 BG 40 5:0) 2 60 7Q gO 90m asad * 


Fia. 46. 


10—26 per cent. calcium they are less stable and decompose 
cold water ; alloys containing higher proportions of calcium 
are still more easily oxidised. Alloys become increasingly 
brittle from 10 up to 40 per cent. calcium, and then there is 
a decrease in this property. 

Zinc does not form compounds with cadmium or mercury, 
nor mercury with cadmium. 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 117 


Compounds of Elements of Group III. with each other. 


The reciprocal behaviour of the elements of this group has 
not yet been closely studied. Tlammann’s first rule holds 
for this group. Gallium, indium and thallium form a com- 
plete series of solid solutions. Thallium and aluminium are 
not miscible in the liquid state according to Doerinckel.! — It 
is probable that aluminium can combine with lanthanum. 

Aluminum-lanthanum.—This system has not been studied 
thermally. Muthmann and Beck? by fusing together 
the two elements have obtained rhombic or monoclinic 
crystals, isomorphous with the compound of cerium and 
aluminium ; their composition corresponds to the formula 
LaAl,. Thetwo metals react energetically on fusion. The 
compound has a white colour ; its specific gravity is 3-928, 
which is approximately equal to the value calculated by the 
mixture rule. 7 


Compounds of Elements of Group IV. with each other. 


Two elements, namely, carbon and silicon, occur in this 
group, which are characterised by great capacity for com- 
bination. We shall have occasion later to deal at length 
with the carbides and silicides ; they are of great importance 
on account of their relationship with compounds of a true 
metallic character. Silicon and carbon form a compound 
SiC called carborundum, which apart from its physical pro- 
perties is of interest because it occupies a position inter- 
mediate between intermetallic compounds and the class of 
compounds to which sulphides and oxides belong. 

Little is known at present of the alloys of titanium, 
zirconium, germanium and cerium with each other and with 
other elements of this group. Cerium combines with tin and 
lead. 

Cervum-tin.—Cerlum forms with tin the compounds 
Ce,Sn, Ce,Sn, and CeSn,. The system has been investi- 


1 Zeit. anorg. Chem., 48, 188 (1906). 
2 Ann. Chem., 331, 51 (1904). 


118 CHEMICAL COMBINATION AMONG METALS. 


gated by Vogel. As the diagram (Fig. 47) shows,” the three 
compounds melt at a temperature much above the melting 
points of their components. Thus CeSn, melts at 1135°, 
Ce, Sng at 1165° and Ce,Sn at 1400°. At low temperatures 
the solubility of the first and the third compounds in their 


























ae 

Ae 

wl LEER 

.| Fae a aS 

SEA | LI 
Ww 





SS 

















ea) 


i NNVNSN 


_-<- 
= _ 
— 
_-_ = 
Lee oe ome awl 








oe ee ee So ee ee ee ee 












































10 40 a0 ke $0 jo go go 100 
_——>2 tae paso Sn - 


Fig. 47, 
components is very small. Ce,Sn separates out at about 
30 per cent. of Sn, CeSn, at 56 per cent. Sn, and CeSn, at 
64 per cent. Sn. The formation of the first two is accom- 
panied by a small degree of super-cooling (up to 15°) which 
however is not observed in the case of CeSng. 


1 Zeit. anorg. Chem., 72, 319 (1911). 
2 In this diagram the proportions are by weight and not atomic proportions. 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 119 


It is characteristic of these compounds that they are formed 
with great evolution of heat, with increasing intensity in the 
order CeSng, Ce,Sn3, Ce,on. 

All the alloys of cerium and tin, with the exception of those 
containing more than 80 per cent. of tin, are pyrophoric ; 
above all, those containing CeSn,. It should be added that 
these alloys are very hard and brittle. 

Cerium-lead.—It appears from the researches of Muth- 
mann and Beck + that cerium has the power of reacting with 
other metals with ease. They isolated by chemical means a 
compound CeAl, ; cerium and zinc, also, combine with great 
heat evolution or even explosion. Cerium and magnesium 
mix with absorption of heat. Investigations with tin and 
lead did not give good results. 

Vogel 2 has studied the cerium-lead as well as the cerium- 
tin alloys. Adding cerium to molten lead a solid homo- 
geneous vitreous alloy is obtained. According to Vogel, 
cerium behaves with lead as with tin, so that the two equili- 
brium diagrams have points of similarity. Further, both 
the cerium-lead and the cerium-tin alloys are formed with 
energetic evolution of heat, giving rise to several compounds 
whose melting points are higher than those of their compo- 
nents, and which are decomposed by water with the evolu- 
tion of gas. The fusion diagram for the cerium-lead alloys 
has, however, not yet been published. 

Lead and tin do not form compounds ; the thermal invest1- 
gation of the system made by Rosenhain and Tukes 3 shows 
the existence of solid solutions between limits. 


Compounds of the Elements of Group V. with each other. 


Nitrogen, phosphorus, arsenic, antimony form a natural 
sroup ; metallic characters are, however, only displayed to a 
marked extent by antimony and bismuth. By reason of 


1 Ann. Chem., 331, 46 (1904). 
2 Zeit. anorg. Chem., 72, 320 (1911), 
3 Phil, Trans., 209 (1908). 


120 CHEMICAL COMBINATION AMONG METALS. 


their affinities, phosphides and arsenides are grouped apart, 
together with selenides, tellurides and sulphides. 

Antimony and bismuth do not combine chemically, but 
form an almost complete series of solid solutions. 

The reciprocal behaviour of vanadium, niobium and 
tungsten is not as yet known. 


Compounds of the Elements of Group VI. with each other. 


Nothing is known of the reciprocal behaviour of chromium, 
tungsten and uranium. The selenides, tellurides and sul- 
phides are dealt with together with the phosphides and 
arsenides. The compounds formed by selenium, tellurium 
and sulphur with the metals of this group do not display true 
metallic characters. 


Compounds of the Elements of Group VII. with each 
other. 


The only metallic element known in this group is man- 
ganese ; the other elements are, of course, the halogens. 
Among these, notable exceptions occur to Tammann’s first 
rule. Chlorine and iodine, indeed, form two compounds, 
ICl and ICl,?, while bromine and iodine form the compound 
Bre 

As these compounds do not show metallic characters it will 
not be necessary to give any data as to their respective 


systems. 


Compounds of the Elements of Group VIII. with each 
other. ; 


This group comprises three sub-groups : (1) 1ron, cobalt, 
nickel ; (2) ruthenium, rhodium, palladium; (3) osmium, 
iridium, platinum. 


1 Cf. Gautier, Contrib. a V Etude des Alliages, p. 114 (1901), Paris. Charpy, tbid., 
pn. 138. Huttnerand Tammann, Zeit. anorj. Chem., 44, 131 (1905). Parravano and 
Viviani, Gazz. Chim. Ital., 40, IL., 446 (1910). 

2 The equilibrium diagram has been described by Stortenbecker, Zeit. phys. Chem., 
3, 11 (1889). 

3 Cf.Meerum-Terwogt, Zeit. anory. Chem., 47, 203 (1905). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 121 


Iron, cobalt, and nickel mix in the liquid state with other 
metals in all proportions, with the exception of tin. Ifa gap 
in miscibility occurs in one case it occurs also in the other 
two. Such lack of miscibility decreases from iron to nickel. 
In the solid state, although these metals generally behave as 
in the liquid state, there are exceptions. or cobalt, accord- 
ing to Levkonja,' Tammann’s rule holds, namely, that a metal 
with a higher melting point can dissolve a greater quantity of 
a metal with a lower melting point than can the metal with 
lower melting point of the metal with higher melting point. 
Tammann’s rule for the elements of a natural group also 
holds for the iron group. If iron does not form a compound 
with other elements, neither do cobalt and nickel. This rule 
has been verified in forty-five cases ; the single exception is 
given by the compound which nickel forms with bismuth. 
Of the forty-five compounds known, the greatest number, 
nineteen, is given by nickel; cobalt gives thirteen and 
iron eight. The most common formula is AB, then AB, 
and A,Bs. 

According to the Periodic System iron, cobalt and mekel 
should each form a group, (1) with ruthenium and osmium ; 
(2) with rhodium and iridium ; and (3) with palladium and 
platinum. Levkonja (loc. cit.) maimtains that his researches 
would appear to give support to the proposal made by Biltz ” 
to reunite iron, cobalt and nickel in a single natural group. 


CoMPOUNDS OF IRON. 


Iron-cobalt—This system was examined by Ruer and 
Kaneko.’ ‘Two series of mixed crystals occur (see Fig. 48), 
one from 0 to 88 per cent. of 1ron—cobalt B, and the other 
from 88 to 100 per cent. iron—iron y. The transformation of 
cobalt B into cobalt «, though occurring along a continuous 
curve from 80 to 83 per cent. shows a maximum correspond- 


1 Zeit. anorg. Chem., 59, 339 (1908). 
2 Ber., 35, 562 (1902). 
3 Ferrum, 11, 33 (1913). 


122 CHEMICAL COMBINATION AMONG METALS. 


ing to the compound Fe,Co,. Alloys belonging to this 
curve exhibit magnetic properties. In the mixed crystals 
between 30 and 83 per cent. of iron the molecules of cobalt 
and iron unite with the compound, which forms mixed 
crystals with excess of the constituents. Below 30 per cent. 
the crystals of Co @ change into crystals of Co a (ferro- 
magnetic). Above 83 per cent., crystals of Fe B are 
formed from Fe y and crystals of Fe « (strongly magnetic) 
from Fe £. | 

Lron-nickel—This system was studied by Guertler and 
Tammann ! and by Ruer and Schiiz.? 

At about 1465° and 66 per cent. of nickel the compound 















































Co Fe 

r) 10 20 30 0 50 50 70 80 90 100 
1550° | 1550 

t ed 

1500° <4 1500° 

_———_———_ 

‘ 
4450° ae 445.0% 
1400° 1400 ° 
Fia. 48, 


FeNi, occurs. The mixed crystals in equilibrium with the 
melt on the first branch of the curve should be considered as 
mixtures of the compound FeNi, with nickel and iron in 
excess, while the crystals on the second branch are to be 
considered as iron y in which nickel is dissolved. These two 
series of mixed crystals are sharply distinguished from the 
crystallographic point of view ; those from 0 to 85 per cent. 
nickel are isomorphous with iron y while those from 35 to 100 
per cent. nickel are isomorphous with the form of nickel 
stable at high temperatures and with the compound FeNi,. 
On cooling the two series of crystals stable at high tempera- 
tures, transformations occur into other species of crystals. 
Jt appears from the study of these alloys that one of the pro- 


' Zeit. anorg. Chem., 45, 211 (1905). 
2 Metall., 7, 415 (1910). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 123 


perties which changes with greatest intensity in these trans- 
formations is the magnetic permeability. 


Compounds of the Metals of Group I. with Metals of 
other Groups. 
Compounpbs oF LirHIuM. 


The behaviour of lithium with beryllium, calcium, stron- 
tium and barium is not known ; with magnesium there is no 
combination, nor is it known whether lithium reacts with zine. 





IDO 1950 


Ne ‘ 
Win 
450 ,\" /] Pe 450 
CET LL 
350 (\! x 1; I5O 


é oy 
4 
s 250 


} 
a Lita | Lita, 








290 









































LI0 : LIO 
OI” OO EO G0 OO 20 GO 90 200 
Lu Ca 
HIG, 49, 


Tithium-cadmium.—Lithium forms two compounds with 
cadmium, LiCd and LiCd,. The system was studied by 
Masing and T'ammann,! and is shown in Fig. 49. Lithium 
and cadmium form an uninterrupted series of mixed crystals 
with a maximum at 50 per cent. of cadmium. The tempera- 
tures at which crystallisation begins can be taken with 
exactness in all cases, but similar precision is not obtainable 
for the completion of crystallisation. As Ruez? has 


! Zeit. anorg. Chem., 67, 183 (1910). 
* Zeit. phys. Chem., 59, 16 (1907). 


124 CHEMICAL COMBINATION AMONG METALS. 


observed, there is at 67-7 per cent. cadmium, in place of an 
interval of crystallisation a marked arrest, and the alloy 
crystallises at constant temperature. A small arrest at 356° 
is noted on the cooling curve of this alloy. The alloy with 
67-7 per cent. of cadmium, in addition to showing an arrest, 
has also a sharp transformation point ; it can be considered 
to be the compound LiCd,. At 50 per cent. of cadmium, 





é Li Hg Lil g Lilt, Lite, 


G>y 4 






































Rig. 50: 


corresponding to the maximum of the curve, another arrest 
point is observed which probably indicates the compound 
hiCd. 

The alloys obtained present a homogeneous appearance ; 
only the alloy with 92 per cent. of cadmium shows a poly- 
hedric structure when treated with dilute hydrochloric acid. 
Alloys containing from 100 to 70 per cent. cadmium are 
stable in the air; with increase in the lithium content their 
oxidisability increases ; thus the alloys with more than 50 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 125 


per cent. lithium become red, those with 13 per cent. of 
cadmium dark brown, and those with still less of this metal 
black. 

Lithium-mercury.—Lithium forms the followmg com- 
pounds with mercury: Li,Hg, Li,Hg, Lig, Lig, and 
Ir a Page 

The equilibrium diagram of the lithium ee is Shown 
in Fig. 50 and has been traced by G. Zukovski.! Kerp, 
Bottger, Winter and [ggena,? studying the amalgams of the 
alkali and alkaline earth metals had already obtained a 
compound LiHg;. Guntz and Férée* admit the existence 
of this latter compound. Maey,* froma study of the varia- 
tions of specific volume with composition, established the 
existence of the compounds LiHe,, LiHgs,, Lidge and Li,He. 

In the diagram traced by Zukovski the maximum point 
of the system is at 50 per cent. mercury, corresponding to a 
compound LiHg. The cooling curve shows other arrests 
from 2:4 to 24-8 per cent. mercury, corresponding to the com- 
pound li;Hg. C represents a new compound which decom- 
poses on melting. ‘The transformation point G indicates a 
new solid phase of the composition LiHg,. (The existence 
of this compound was confirmed by calorimetric measure- 
ments.) The point H represents the compound LiHg,. In 
the rest of the curve no other arrest points are noted, which 
contradicts the contention of other workers as to the occur- 
rence of acompound LiHg;. The compound LiHg separates 
in needle-shaped crystals. 

Inithiwum-tin. — Lithium combines yay tin forming the 
following compounds :— 


isons, luton, and bon. 


The diagram has been worked out by Masing and ‘l'am- 
mann ° and is shown in Fig. 51. Adding lithium to tin, the 


1 Zeit. anorg. Chem., 71, 403 (1911). 
% Tbid., 25, 16 (1900). 

3 Bull. Soc. Chim., 15, 834 (1896). 

4 Zeit. phys. Chem., 29, 119 (1898). 
5 Zeit. anorg. Chem., 67, 183 (1910). 


126 CHEMICAL COMBINATION AMONG METALS. 


melting point of th latter is lowered until the eutectic point b 
is reached, corresponding to about 95 per cent. of tin. The 
cooling curve of the alloy of this composition shows an 
arrest at 214°, and the structure of the solid alloy is eutectic. 
Adding more lithium, the lquidus curve rises along the 
branch b c. The compound Li,Sn, first separates at 320° 
and 72 per cent. of tin in the form of white crystals, sur- 









































A hy 100 
GOO te 608 
iY 
ey) 
500|—_ rer eais 500 
' ¢ 
' (ML . Z Thy 
400 . “yf Yy > 400 
300 SW y 300 
/j Nb 
200)! Ca + 200 
a ts: 
100 100 
Ly | Sz | LrypSIe , Lig Si, 









































GO LW COM TIO LO GOT LOO AOE OO, IS LUG 
$22 
Fi@. 51. 


rounded by the eutectic, which slowly become yellow when 
exposed to the air. At 465° and 40 per cent. tin a slackening 
is shown which corresponds to the compound Li,Sn,. The 
reaction between Li,Sn, and the melt c does not take place 
completely, for the eutectic horizontal b o extends beyond 
the point », which corresponds to the composition of Li,Sn,. 
In consequence, alloys containing less than 77 per cent. of 
tin are composed of three species of crystals; the crystals 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 127 


Li,Sn, are surrounded by Li,Sn,;, and among the latter is 
found the eutectic b, containing tin. The crystals of LigSn, 
are long, and on exposure to air become first yellow and 
then brown. From e the curve rises rapidly to the maxi- 
mum f at 20 per cent. of tin, which probably corresponds 
to the compeund li,8n. The crystals at this point have a 


900° 





800° | 





ZOO” 





600° 











500° 


MLE. 


NaLr,, 


900 cine s 















































micaceous structure and are very brittle; they acquire a 
dark blue colour on exposure. 


COMPOUNDS OF SODIUM. 


Sodvum-magnesium.—Sodium forms no compound with 
magnesium. The system was investigated by Mathewson.! 
Sodium-zinc.—With zine, sodium forms the compound 


' Zeit. anorg. Chem., 48, 193 (1906). 


128 CHEMICAL COMBINATION AMONG METALS. 


NaZn,, or NaZn,,. The equilibrium diagram, due to 
Mathewson (loc. cit.), is shown in Fig. 52. The two metals 
are only slightly soluble in each other even at high tempera- 
tures. At 557°, zinc dissolves about 6 per cent. of sodium, 
while sodium scarcely dissolves zinc at all. However, at 





= 


Wa Ca, 





————______ +} 


300° 























50 





200° 





Wea Ca, 





Wa Cal, 


; 
ZATION 
GZ 
cS 
CEOs 
MM 





| 
vi 
4 
z 
A 
y 
Vj 
V 








50 















































0 10 10 % 0 40 50 60 76 _ gO 90 CO 
eee OCCA Clown Ma 


Fie, 53, 


about this temperature and at a concentration of 8-86 per 
cent. of sodium a compound is formed of uncertain formula, 
for while the diagram suggests NaZn,, as most probable, 
analyses of the lower strata of certain melts give NaZnj4p. 
Oa melting, the compound gives a liquid richer im zinc 
together with almost pure sodium. 

The compound is harder and more brittle than zinc, and 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 129 


on exposure to air is slowly covered with a white layer of 
zinc hydroxide. 

Sodium-cadruwm.—With cadmium, sodium forms the two 
compounds NaCd, and NaCd,. Fig. 58 gives the equilibrium 
diagram of this system, studied first by Kurnakoff,' then by 
Mathewson,” and finally by Kurnakoff and Kusnetzoff.? 
The diagram shown is due to Mathewson, who has estab- 
lished, both by means of thermal analysis and also directly 
by removing the liquid in a pipette, the gap in solubility 
which occurs from 30 to 40 per cent. of cadmium. Two 
maxima are observed corresponding to the two compounds, 
for NaCd, at 360° and 16-4 per cent. sodium, and for NaCd, 
at 382° and 33°06 per cent. of sodium. According to Kurna- 
koff, in the place of NaCd;, NaCd, is formed. Mathewson 
does not report the occurrence of mixed crystals ; Kurna- 
koff, on the other hand, states that NaCd, can dissolve a 
certain quantity of NaCd, im solid solution. 

The compound NaCd, is shining and brittle. The alloys 
of the compound NaCd,; and the eutectic are harder and 
show a finer structure than the compound NaCd,. The 
alloys of the compound NaCd, and the eutectic with 16 per 
cent. of sodium can be cut with a knife. The compounds 
are harder than cadmium; Nad; is as hard as cale spar, 
and NaCd, is a little harder. 

In moist air both compounds are oxidised, NaCd, more 
rapidly than NaCd;. 

Sodium-mercury.—The sodium amalgams are very diverse 
and include compounds of the following formule :—Na,Hg, 
Na,;Hg,, Na,Hg,, NaHg, Na,Hg,, Nag, and NaHg,. 

The system was studied thermally by Schiiller,* who 
reports the existence of a compound Na,.Hg,3, while 
HK. Vanstone ® from a study of the specific volumes of the 


1 Zeit. anorg. Chem., 28, 439 (1900). 
2 Ibid., 50, 180 (1906). 
8 Ibid., 52, 173 (1907). 
4 Tbid., 40, 385 (1904). 
5 Chem. News, 103, 181, 198, 207 (1911). 


130 CHEMICAL COMBINATION AMONG METALS. 


system sodium-mercury believes the existence of a com- 
pound Na-;Hg,; more probable. 

Fig. 54 shows the equilibrium diagram for sodium-mereury. 
The compound NaHg is formed at 50 per cent. sodium and 
219°, with such strong super-cooling, however, that the corre- 


Paes 
100 _—- 














































































































ee 
Naz, 
So 
Oe 
5001. Na Xo, ae AN 
; Lily | 
fags. 
tag : 
2001 ' LV |xNelHon* Yap 
| ‘ Na, Hy 
j Lip “tbacal// 
50 iiaee= = Vg $4 
i Vii ee he £4 ” 
¢ Ke 
100 oe: Nao 2 ges 
<< : ' 4 
50 [ BS ee 4 ae = ih “Sy, ON 
N\ aA A = <7 
eee neoe PO In SS 
cae eas S ss | |S | l 
N or 5 ieee BAY 
~ ~~ Nay 7g {oe rh ae 
iS Ne lao las | ee 
Hy anes 1X - 
; Wa Hy, > 17 ie vies 
0 10 1Q 30 40 50 GO 40 §0 GO SELOG 


es Oo, Na. 
Fie. 54, 


sponding arrest points are not found on the horizontal as 
would be expected. An imperfect equilibrium is established, 
and hence the arrest points at 123° show a quantity of sodium 
less than 50 per cent. At 61 per cent. of sodium and 125° 
the compound Na,Hg, is probably formed ; in this region, 
also, super-cooling is observed. Na, sHg,3 is shown by a 
discontinuity at 227° and 48 per cent. of sodium. But, as 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 181 


has already been said, the formula of this compound is 
uncertain. The formule attributed to the other compounds 
may be considered reliable. Mixed crystals are formed 
among the compounds. 

Sodium-aluminium.—Sodium forms no compounds with 





Na|77 


50 





Weve Neer? 














EB py OS SOE SA 






























































200° MN 
| NN 
| Ee : KS 
50 | (7 
| y 
Noo” 3 Nel? Se : AN 
ee : eas, 
[Ne 7 ‘4 Na, Lie A 
50 7 “4 ae ‘ 
vee , 
] | | 
oO ; eee 
0 10 rissa We LO 50 ipa e 70: - 90: 400 
Fig. 55. 


aluminium. ‘The system has been studied by Mathewson ! 
and Smith.” 

Sodvum-thalluwm.—tThis system was studied by Kurnakoff 
and Pushin,? who have established the existence of the com- 
pound NaT!, which agrees with the monovalency of thallium. 
The diagram shown in Fig. 55 indicates the existence of two 
other compounds which separate respectively at 158° and 


| 33 per cent. thallium and 77-9° and 17-2 per cent. thallium ; 
1 Zeit. anorg. Chem., 48, 192 (1906). 


2 [bid., 56, 112 (1907). 
8 Ibid., 30, 87 (1902). 


182 CHEMICAL COMBINATION AMONG METALS. 


it is doubtful, however, if the formule Na,Tl and Na, 
attributed to them are reliable. Na'T'l crystallises in three- 
rayed arboriform growths, and is formed with considerable 
development of heat. The melting point of this compound 
is 805-8°, or somewhat higher than that of pure thallium. 
The compound is harder and more brittle than its compo- 
nents. 

Sodvum-tin.—Sodium forms the following compounds with 

















NaS 
700° Na, fn 
Nea S: Na, Sr, 
ue | | Na, Sn 
600 : | 
| a 
Zee 1 
: A f 
~ SOR Rh P 








208 MX 


\ 
SNe le 
ee 


Nal Soe A aSn ~NaSn i 
Sn LZ, ott fie see |g | WaSe, 
f * 1 T7 « 
































* 












































° 15S ea a! 
Se ea Y 
400° V me 
fe) 10 20 30 40 50 GO 49 80 90 100 








Qn Obonr Now 





Fig. 56. 


tin: Na,Sn, Na,Sn, Na,Sn3, NaSn and NaSn,. The system 
has been worked out by Mathewson,! and its diagram is 
shown in Fig. 56. The fusion curve shows two distinct 
maxima. The compound in equilibrium with the melt 
at 405° and at a concentration of 80 per cent. sodium has the 
formula Na,Sn. At 405° it decomposes to a melt of com- 
position indicated by B and the compound Na,Sn. The 
latter compound corresponds to the maximum at 66-9 per 
cent. sodium and 477°, while Na,Sn, occurs at 57 per cent. 


1 Zeit. anorg. Chem., 46, 94 (1905). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 1388 


of sodium. At 478° the latter decomposes, forming crystals 
of the compound NaSn, which is found at the maximum point 
at a concentration of 50 per cent. of sodium. At 483° a 
polymorphic transformation takes place. Finally NaSn, 
is found at 33-5 per cent. sodium. When warmed it decom- 














































































































$00°|. = 
Na. PB ar 
alae Wal Pb 
$0 
Na, / 3s 

400° | 

50 BOO 

Va OAD ROR 
| Pr 
ins Kaa, = Aten / eh 
ler 
50 
5 
900° rie d 
me i Gi 

a ; ; Yi 

200° Uy Me 
| 
50 ee ea 
oO 410 20 30 4,0 5O 60 iO" 80. 9O 400 


ee a ON en NG: 

Fig. 57. 
poses at 305° into crystals of the compound Nadn and a 
melt containing about 20 per cent. sodium. 

Freshly cut, NaSn, has a steel blue colour ; Nang, has a 
pale blue colour ; the other compounds are similar in colour 
either to sodium or to tin. 

The compound Na,Sn, is fairly hard and brittle; the 
other compounds are more brittle. The latent heats of 
fusion have been calculated approximately from the 


134 CHEMICAL COMBINATION AMONG METALS. 
thermometric arrests by Tammann’s method; the values 
obtained are as follows: Na,Sn=11; Na,Sn = 12; 
Na,Sn, = 11; Na,Sn, (transformation) = 4; NaSn = 14; 
NaSn (transformation) = 7; NaSn,=9; NaSn, (trans- 
formation) = 4. 

Sodium-lead. — This system was studied by Kurnakoff,! 


900° 


i Kalb | 


WD 

i LZ, 
oe VY GD 
MLD) | WZ 
lta 

pres WU 





aN 











aS 








a a 


§ 
ae \ 
NS 
SS 
he 
SA 
r 
\ 
\ 











SOM Ss 


IN 





SS 












































O 10 40 0 40 50 GO 70 gO 90 100 
Fig. 58. 


and later by Mathewson,? who have noted the occurrence of 
the following compounds :— 

Na,Pb, Na,Pb, NaPb and Na,Pb;. The curve of fusion 
is shown in Fig. 57 taken from Mathewson’s paper and 
exhibits four maxima, the first at 886° and 80 per cent. 
sodium, the second at 405° and 67-2 per cent. sodium, the 


1 Zeit. anorg. Chem., 28, 439 (1900). 
2 Ibid., 50, 172 (1906). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 135 


third at 367° and 49-6 per cent. sodium, and the last at 
819° and 28:2 per cent. sodium. Some doubt, however, 
exists about the compound Na,Pb;, which might be replaced 
by the compound NaPbs. Mathewson, however, decides for 
Na,Pb;, seeing that while its melt shows a sharp arrest point, 
that of the second only gives a discontinuity. 

Two of the compounds, Na,Pb and Na,Pb, form mixed 
crystals with each other. The alloys of this series oxidise 
easily—those with high sodium content more easily than 
those with low content of this metal. As to hardness, 
NaPb and Na,Pb,; are almost as hard as cale spar, while 
Na,Pb and Na,Pb are rather less hard. Na,.Pb has a light 
blue colour, while NaPb 1s light grey. 

Sodium-antumony.—Sodium combines with antimony, 
forming the two compounds Nas,Sb and NaSb. Fig. 58, 
taken from Mathewson,! is the fusion diagram. ‘Two 
maxima are shown, one at 856° and about 75 per cent. 
sodium, corresponding to the first compound, and the other 
at 465° and 50 per cent. sodium, corresponding to the second 
compound. NaSb is almost as hard as gypsum and 1s of the 
same colour as antimony, while Na,Sb 1s deep blue and some- 
what harder. The sodium-antimony alloys ignite spon- 
taneously in the air. 

Sodium-bismuth.—This system has been investigated by 
Kurnakoff? and Mathewson.? The diagram (Fig. 59) shows 
the existence of the two compounds Na,Bi and NaBi. The 
first is indicated by a distinct maximum at 775° and 75:15 
per cent. sodium, the second is represented by a break and is 
formed at 445° and about 49 per cent. of sodium. Here also, 
as in the case of NaSb, the two metals develop heat strongly 
on being melted together. Na Bi has a violet blue colour 
when freshly cut; pieces larger than 10 grams inflame 
spontaneously in the air on slight heating. The hardness 


1 Zeit. anorg. Chem., 56, 192 (1906). 
2 T[bid., 23, 439 (1900). 
3 [bid., 50, 187 (1906). 


1386 CHEMICAL COMBINATION AMONG METALS. 


of the two compounds is almost equal to that of bismuth and 
of cale spar. 


PotasstumM COMPOUNDS. 


Potassvum-zinc.—Potassium forms a compound with zine 
whose probable formula is KZn,, or KZn,,. The system was 
















































































: LILI, 
~ iy 
BALSAM, 

: Uff 

. . Z DER hed 4 Li 

ER VM WZ 

Pie ane LLL 
10) 40 20 30 4O 50 Mae te cas 


Fig. 59. 


studied by Smith.t As Fig. 60 shows, the two metals havea 
very small reciprocal solubility at 600°, since at that tem- 
perature most melts consist of two liquid strata. At 585° a 
metastable form of the compound separates, passing into | 
the stable form when the solidification is scarcely complete. 
Between 405° and 510°, from 9 to 40 per cent. potassium, 
thermal! effects are indicated. The horizontal at 510° marks 


t Zeit. anorg. Chem., 56, 113 (1907). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 187 


a transformation of the compound KZn,,. The structure 
of the alloys is finely granular. They are easily altered in 
the air. 

Potassiwm-cadmium.—Potassium combines with cadmium, 
forming the compounds KCd,, and KCd,. Fig. 61, taken 
from Smith? is the fusion diagram. The mutual solubility 


























R30, 
700" : | 
7 
ra 
v4 
6004 ae 
Ee) Se LOAD AO Le SS ii 
gy 
V/ 
loo | Ley oy a 








300° 











¢ 
200 


wl AALS, 
Zn ! 
Uy Bk DOES: 


























of the metals is small. At 468° there is a gap of solubility 
between 17 and 99 per cent. potassium. At 478° and 12-5 per 
cent. potassium, KCd, separates and at about 485° and 7 per 
cent. potassium, KCd,,. The formula given to the latter is, 
however, not perfectly reliable ; IKCd,, might be substituted 
for it. 

These alloys oxidise easily in air. 

Potasswum-mercury.—The potassium amalgams, like those 


1 Zeit. anorg. Chem., 56, 113 (1907). 


1388 CHEMICAL COMBINATION AMONG METALS. 


of sodium, are numerous. Kurnakoff! first studied the 
system and his data were later confirmed by Jainecke.? The 
compounds probably formed are KHg, KHg,, KHg,, K,Hg., 
and KHz, all of which Kurnakoff admits with the exception 
of K,Hg, whose formula he believes to be KHg,. 

Fig. 62 gives the fusion diagram. The compound KHg, 
which melts at 178°, is shown by a discontinuity in the curve; 
the compound KHg, alone shows a maximum, which occurs 





50 KCd KCd, 


a ee J 









N 


SOL 




















6 ¥0 8080. Lo 50 86 4G. 6° 90 FOO 
Sas ie in Cilonre c cl 





Fia. 61. 


at 279° and about 65 per cent. of mercury. The other com- 
pounds are formed in a limitel concentration interval, 
KHeg, occurs at 204° and 78 per cent. mercury, K,Hg, at 173° 
and about 838 per cent. mercury, and KHg, at 70° and 90 per 
cent. of mercury. The homogeneity of the last three, on 
which some doubt might be cast, is shown by microscopic 
analysis, for the first crystallises in rods about one centi- 


1 Zeit. anorg. Chem., 23, 439 (1900). 
2 Zeit. phys. Chem., 58, 245 (1907). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 189 


metre long, the second in hexagonal plates, and the third in 
regular, mainly cubic form. 
Potassvum-thallium.—As noted by Kurnakoff and Pushin,! 


potassium forms with thallium the compounds KT] and 
Iceni 























200° 
Kg, 
so | 
K, My" 
K, Ay, ? 
300° | Atty 
y 
50 ws Dp 
| Rhy 
200° LM 
(efe) 2 Z 
Ae? BS | VLE 





$c 


~ 
Aoo° AN 


: es 2 i GAG : K 
| 





S 
S 

































































Mae Se se eee LZ] LA 
' 
eee Kk, 
0° 2 flee 
a) ; 1 * 
Ne | K k19 KH7 
-50 lA, Foy? 
| # 
fly + | 
KHy, ? [dss A 
-4o0° ! : 
9 % 0 50 0 0 8 Jo 100 
eae, ‘oO fe) () 4 60 ae Siete 
Fie, 62. 


The equilibrium curve is shown in Fig. 63. The existence 
of the second compound has been established by analogy 
with the behaviour of sodium with thallium, since the dis- 
continuity which is found at 242° and 32:9 per cent. is not 
very pronounced. At 335°, the curve shows a maximum, 
corresponding to KTI. The melting point of this compound 

1 Zeit. anorg. Chem., 80, 87 (1902). 


140 CHEMICAL COMBINATION AMONG METALS. 


is, as may be seen from the diagram, somewhat higher than 
that of pure thallium. The compound KT! crystallises in 
compact brittle cubes, which react with moist air. It 1s 
formed with considerable evolution of heat. 
Potassivum-tin.—Potassium forms with tin numerous com- 
pounds, from which, however, K,Sn, corresponding to the 
saline valency of tin, is lacking, although a corresponding 
400 











K77 
50 Y 1 O02 Gan 
Dl | a fe 
50 Ke as 





Es ae 
AS 
2001 N\ 


KON 





50 





x 
ie 
ha 


.. 
ree SASSY 
WC 
\ 
Sa 















































aie YZ. 
uae WE 
: : | ATI GA é LaLa 
| | ox 
as K\- K. 7 
Ae 3 20 ce 40 50 60 40 gO 90 109 
Fig. 63. 


sodium compound occurs, Na,Sn. The following are the 
potassium-tin compounds: KSn,, KSn,, KSn and K,Sn. 
Fig. 64 indicates thé diagram of the system which was 
studied by Smith.t The melting points of the alloys are, over 
a certain range, above the boiling point of pure potassium 
(757°). KSn, separates at 600° and 20 per cent. potassium 
from the melt and from a compound of uncertain formula, 
possibly KSn,, formed at a higher temperature. At above 
1 Zeit. anorg. Chem., 56, 129 (1907). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 141 


600° and 50 per cent., KSn is formed which, reacting with the 
melt, gives the compound K,Sn (?) with a maximal arrest 
at 535°. 

Potassium-lead.—Smith?! has also studied this system in 
which the compounds KPb,, KPb, and K,Pb are formed 
as indicated in Fig.65. In this series the type K,Pb, which 
occurs in the sodium-lead system and corresponds to a saline 


9c0 


























: KSn, be KSr Ib San 
8004 eal Y 
VA. 
790" ZN 
Oe : j 

600° PS Z Z Lp, 

AN ks Z WLM, me 
500° pos ae Beall : 


Sar 
oe 
g. 
a 
~ 
YY 
SS 





aco" [SRE SGAS SO 

































































| 
x OL tN 
OO Y A Wp 

200° a ae Wag 
5 GOD 

Aoo° wa ek, ee go UG ; d 
70 10 Lo 30 40 50 60 oO 60 90 100 

ee oe tllonas Kh 


Fig. 64. 
valency of lead, is missing. At 568°, between 35 and 75 per 
cent. of potassium, a compound crystallises out from the two 
liquid strata to which the formula K,Pb is given. At 380° a 
transformation occurs, probably into another form of the 
compound. At 337° and 33-33 per cent. potassium, KPb, 
is formed, while at 295° there separates from the crystals of 
this compound, and from the melt, KPb,, whose formula is 
not, however, well established. It is, further, uncertain 


4 L00. Cit. 


142 CHEMICAL COMBINATION AMONG METALS. 


whether the eutectic horizontal at 876° consists of two hori- 
zontals, of which one corresponds to a compound X between 
K,Pb and KPb,. Smith did not observe an eutectic point 
between K and K,Pb ; yet the alloys between 65 and 98 per 
cent. potassium show a point of arrest 4° to 6° lower than the 
melting point of potassium. 
Potassium-antimony.—Although we have no very exten- 











































































































A343 
| a 4 
600 er ; 
; se Yd Li, ZA) 
500 VV, ae wz L WN) 
. LE 
| ERE 
200" BRS, ox m8 T + és vee 
a i a p 
200" = ! Ki PS yy 
J 4 lalal § | WAZ 
Pte (LAA 
a KP&, J 
0 10 20 %0 40 50 GO #O 8O qo loo 


So in Oho. IK 





Fi. 65, 

sive knowledge of the compounds between potassium and 
antimony, it is well established that the two elements do 
combine. The system potassium-antimony has recently 
been studied by Parravano.! The diagram is shown in 
Fig. 66. It will be seen that the curve is quite simple and 
shows the existence of the two compounds K,Sb and KSb, 
having melting points at 812° and 605° respectively. The 
formation of these compounds is attended with a consider- 

1 Gazz. Chim. Ital., I., 485 (1915). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 148 


able evolution of heat. The compound K,Sb, in which the 
trivalency of antimony is shown, has a yellowish-green colour 
and alters rapidly in the air ; the compound KSb crystallises 
in long slender prisms of a colour similar to antimony and is 
less rapidly attacked by air than the former compound. 


Ry Sb 
; 


‘ 
‘ 
fool 
‘ 
’ 
: 
‘ 


boc} 


.t YU 








JQOF 




















K 30 80 yo 60 20 6o0 30 ac 10 r 
10 10 so 4a 20 60. lo ¢Q 3° $d 


FIG. 66. 


Potassium-bismuth.—Potassium combines with bismuth, 
according to Smith! to form a rather numerous series of com- 
pounds. They comprise KBi,, K,Bi, (?), K,Bi, and K,Bi. 

Fig. 67 is the diagram for this system. K,Bi gives a 
maximum at 75 per cent. of potassium and 671°. At 286°, 
arrest points occur between 60 and 83 per cent. of potassium, 

1 Zeit. anorg. Chem., 56, 125 (1907). 


144 CHEMICAL COMBINATION AMONG METALS. 


with a maximum at 75 per cent. These probably indicate a 
transformation of a K,Bi into g K,Bi a companied by an 
increase in volume. Further, at 420° with a maximal arrest 
at 60 per cent. potassium, a compound, probably K,;Big, 
separates. From these crystals and the melt at 54 per cent., 
another compound separates at 378°, also of uncertain 
formula, K,Bi,. Another maximum occurs on the curve at 








































































































&c0° 
Ky Be 

i Ki, A, Be, | 
rqefe) | t 
¢00% : ISS 

< Kobi | ASSN 

LLL) KNB IRS 

$ec ZL eke 
YY UL AAEETNNAN 
e YUL XS SSXQ 
YU AO gtiN 
y, Yy) pay ae 4,2, ORO \ 

3005 Vhs Hae ara JK Be BOs Bs 

WAZA AT | Sas 
: . Ys 
2co° S ~ SR 

eee B, Be, Le S , 
100° : * Nt ZN SESS 1 
SSS 

0° A Yai 4 Zr EP Aee =/) 

0 10 20 30 40 50 co 700 ¥O 90 uo 





Fig. 67, 


about 550° and 33-33 per cent. of potassium, due to a com- 
pound whose formula can safely be taken as KBig. 

The two metals develop a considerable amount of heat on 
being melted together, due, it is maintained, to the formation 
Of Keb | 

Rusipium COMPOUNDS. 


Rubidium-mercury.—Little is at present known of the 
compounds of rubidium with other metals. The system 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 145 


rubidium-mercury has been studied by Kurnakoff and 
Zukovsky,' but only over a limited range of concentration. 
The existence of a compound RbHg, was noted, which 
melted at 136-5° with decomposition. At 70-2° there is a 
transformation point, and here a compound richer in mer- 
cury begins to separate, to which, by analogy with the corre- 
sponding cesium compound, the formula RbHg,, may be 
given. 
Cmstum COMPOUNDS. 


Ceesvum-mercury.—Our information on the metallic com- 
pounds of cesium is also very scanty. The compounds with 
mercury are well known. The system cesvwm-mercury 
studied by Kurnakoff and Zukovsky (loc. cit.) is shown in 
Vig. 68. The following compounds are formed: CsHgy, 
CsHg,, CsHg,, CsHg,, CsHg and Cs,Hg. 

Three maxima are seen in the diagram representing the 
three compounds CsHg,, CsHg, and CsHg, respectively. 
They occur at 208-2° and 67 per cent. mercury, 163-5° and 
80 per cent. mercury and 157-7° and 86 per cent. mercury, 
and melt without decomposition. _ At 188° weak arrests are 
noted between 62:4 and 65-8 per cent. mercury, which 
probably imply a polymorphic transformation of the com- 
pound CsHg,. The formation of solid solutions is observed 
on the curve. At 13-1° and 91 per cent. mercury, the com- 
pound CsHg, is transformed into CsHg,); this formula is, 
however, not well established. Other arrest points occur at 
50 per cent. and at 37 per cent. of mercury (CsHg and CsHg,), 
but as to these compounds there 1s considerable uncertainty. - 


CopPpER COMPOUNDS. 


Copper-berylliwm.—tittle is known of the beryllium alloys. 
The alloys with copper have only been studied by Lebeau # 
and, more recently, by G. Oesterhe!d,? who studied the system 

1 Zeit. anorg. Chem., 52, 416 (1907). 

2 CO. R., 125, 1172 (1897). Bull. Soc. Chem., (3), 19, 64 (1898). Ann. Chim. Phys., (7), 
16, 498 (1899). 

3 Zeit. anorg. Chem., 97, 6 (1916). 

C.M. 10 


146 CHEMICAL COMBINATION AMONG METALS. 


over a limited range. The compound CuBes occurs. The 
melting point of copper is lowered until a concentration of 
10 per cent. beryllium is reached, and the lowering is accom- 
panied by the formation of solid solutions. Beyond this 


























































































































G Hy, { ( CEG 
90042) iin | 4%. i, 
| 
| | fe | Og Tf. 
yr 5_ “77 
. NY : 
' PAL 
al CB (ao se 
eat Pn, 
3 SR oN 6, Sa 
\ Pe a lib 
Lf as 
aoe C3119, ey 
es | | i, 
10 OF baie ASE CsH9, { Hs 
BS ll ary WY) 
Sh] y iY, 
zs Nae = Cs Hg, oe LM, 
oN | if | ee Vy 
Ke Bes © } ALND, 
50 a Is | 4 vA oe 
SNE muy 
SN MK 
25 ae oo | as ws oA a 
wy LLL 
LOS | 
On Vly, oe ee 1 
Use| ! 
C3. 4 
25 bas C9 | 4 
es : 
ste 
= 50° ert! N che : 
Q 10; 74) *90 40 50 60 70 gO 90 1090 


a ee uc Cbonre Cs 
FIa. 68. : 


limit for a short interval the solidus and liquidus curves have 
an unusual form and subsequently pass through a minimum 
and a point of inflection. At 575° there is an eutectic point 
for 381 per cent. beryllium, and thence the curve rises to a 
maximum corresponding to the compound mentioned. 

The copper-beryllium alloys can dissolve in nitric acid. 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 147 


Copper-Magnesitum.—Copper forms with magnesium two 
compounds, namely, CuMg, and Cu,Mg. The system has 


000% 





$0 





° 
4000 


A 


b0° 

















YG 
Yi 










































































LA & 
Vy Y LOSS SS 
Z700° WE Coa 
Ze 
: as UML. 
: VY, Y 
oD WG me 
as AWS Li ie i 
Or or 
ot LD Pak uA Cu lg, 
[LMC SIE . 
Cu, 
a 10 ae? 90 40 50 60 70 80 70. FOO 
pF Olona Cin 
PiG.+69: 


been studied by several workers, including Boudouard,! 
Urasoff ? and Sahmen.? 


1 C. R., 135, 794 (1902). 
2 Chem. Centr., 1908, I., 1038. 
3 Zeit. anorg. Chem., 57, 26 (1908). 
10—2 


148 CHEMICAL COMBINATION AMONG METALS. 


The data obtained by the two Jatter are quite concordant. 
As Fig. 69 shows, there are two maxima, one for Cu,Mg at 
33:3 per cent. magnesium and 797°, and the other for CuMg, 
at 66:7 per cent. magnesium and 570°. Mixed crystals are 
lacking in this system. Boudouard also reports a compound 
CuMg. Sahmen states that the eutectic point between 
Cu,Mg and CuMg is found between 55 and 57 per cent. of 





4100" 


CuZln 


4 lad a, 
AGOO Cc Lee som 
2 oe Bd 








800° 














i 
\y 


r 
@00 

















x LE; 


XN 
\ 
Eee (al ay, CE 
@i=eoe 
g 








-——_— 
ee ee ae 















































eyo Ge eee | 
| Ba ee, ' 
| One A ! | | 
| 
| aA f ashe | | 
Joo } a . | = 
oO 10 OMe} 40 4,0 40 éC nee SO 4a 4090 
’ pete ee Se aa Cows Cre 
Fie. 70. 


magnesium, While according to Urasoff it is found at 58-5 per 
cent. of magnesium. Both compounds are very brittle and 
have the colour of pure magnesium. Only those alloys rich 
in copper which contain a large quantity of that metal in the 
free state exhibit a red colour. 

Copper-zinc.—Copper combines with zinc, forming the two 
compounds Cu,Zn, and CuZn. The equilibrium diagram of 
these alloys has been investigated by Roberts-Austen,! 

1 Proc. Inst. Mech. Eng., 1897, p. 31. 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 149 


Shepherd,! Tafel,? Carpenter and Edwards,? and lastly by 
Parravano.* As is seen from the diagram, which epitomises 
our knowledge of the brass alloys (see Fig. 70), Cu,Zn, 
separates at 833° and 60 per cent. zinc, and CuZn at 1005° 
and about 50 per cent. It was noted that the region of 
existence of this latter compound became more restricted 
with fall of temperature. 

Shepherd maintains that the curve does not necessitate 
. the unconditional admission that compounds are formed. 
Bornemann? refutes this for various reasons. Above all be- 
cause the field of existence of homogeneous 4 crystals enlarges 
with fall of temperature towards the Zn axis. The solubility 
of the substance richer in zinc inthe solid solution indicated 
by @ increases with fall of temperature. The solution 
process must be exothermic and an exothermic compound 
must be formed. ‘To support his contentions, Bornemann 
cites the work of Backer ® and Herschkovitch? on the heats 
of formation of the copper-zine alloys ; for all concentrations 
the values obtained were positive. Further, allowing the 
existence of the compound, and this Tafel holds to be certain, 
as well defined and practically undissociated in the pure 
state, the micrographic study and the diagram should be in 
perfect agreement. 

To resolve the question, Bornemann examined the methods 
used to determine the constitution of compounds by observ- 
ing the relation between concentration and (a) electrical 
conductivity and temperature coefficient of electrical resis- 
tance, (b) specific gravity and specific volume, (c) electro- 
lytic potential, and (d) chemical and_ electrochemical 
reactivity. In all cases the presence of compounds is dis- 
tinguished from the presence of mixed crystals, since the 

1 J. Phys. Chem., 8, 421 (1904). 

2 Meétallurgie, 5, 349, 375 (1908). 

3 Int. Zeit. Metall., 2, 129 (1912). 

4 Gazz. Chim. Ital., 44, I1., 475 (1914). 

5 Die binaren Metallegierungen, p. 19, Halle, 1909. 


8 Zeit. phys. Chem., 38, 630 (1901). 
? Ibid., 27, 164 (1898). 


150 CHEMICAL COMBINATION AMONG METALS. 


formation of the former produces much more marked 
changes than the latter. 

(a) Le Chatelier } and Guertler ? with regard to the first 
method have laid down the following rules: (1) the curve 
of concentration-electrical conductivity is practically a 
straight line in all cases where an alloy consists of a hetero- 
geneous mixture of two constituents ; (2) wherever mixed 
crystals occur the curve shows a marked lowering. The 
measurements carried out by Matthiessen,? Haas,’ and 
Weber,°® show that while the existence of the compound 
CuZn is probable, other compounds do not exist between this 
and pure copper. The compound Cu,Zn, may exist although 
apparently it shows no maximal conductivity. 

(b) Specific volume should change in a linear manner with 
concentration in the case of heterogeneous mixtures. In the 
case of mixed crystals a change from one series to another 
should be marked by a discontinuity in the curve. If at the 
point of discontinuity mixed crystals do not exist the new 
phase is to be taken as a compound. ‘The diagram showing 
Maey’s ® observations shows no marked discontinuities with 
the exception of one at 40 per cent. copper, corresponding to 
the compound Cu,Zns. 

(c) With regard to electrolytic potential two principles 
must be noted : (1) where mixed crystals occur the potential 
should fall in a continuous curve; (2) mn heterogeneous 
systems of saturated mixed crystals the potential should 
remain constant. In the case where compounds are present 
without the formation of mixed crystals, each compound 
must be reckoned as a single new substance, and the 
diagram is divided up accordingly into corresponding parts. 
A compound should be marked by a decided fall of potential. 
In practice the distinction between mixed crystals and com- 


1 Rev. Génér. des Sciences, 6, 531 (1895). 

2 Contrib. a V Etude des Alliages, Paris, 1901, p. 446. 
* Rep. Brit. A3s., 1863, 127. 

4 Wied. Ann., 52, 673 (1894). 

> Tbid., 68, 705 (1899). 

® Zeit. phys. Chem., 38, 291 and 299 (1901). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 151 


pounds is not so simple, since most usually the fall of 
potential extends over a certain range of concentration and 
is graphically represented by a curve. Consequently it is 
necessary to examine also the fusion diagram. Pushin’s ! 
curve, though showing some errors in measurement, indi- 
cates a sharp fall of potential! corresponding to 60 per cent. 
zinc, .e., to the compound Cu,4Zn,. Another, though small, 
fall takes place at about 50 per cent. and may correspond to 
strongly dissociated CuZn. The other falls of potential 
given in Pushin’s curve are very probably not due to com- 
pounds. Sackur,? by chemical means, has demonstrated 
two considerable falls of potential. 

(d) Sackur,’ and Lincoln, Klein and Howe * have studied 
the chemical and electro-chemical reactivity of the copper- 
zinc alloys. ‘The former has determined the solubility of 
alloys in dilute acids in the presence of air. He observed 
that there were distinct changes for the crystals 8 and y, and 
these may consequently be compounds. The other authors 
studied electrolytic reactivity in neutral saline solutions, 
obtaining hydrates or basic salts which were mechanically 
removed from the anodes. From their curve it appears that 
at about 40 per cent. the quantity of copper oxidised is 
reduced almost to nothing, which is another proof of the 
existence of the compound Cu,Zn3. 

Summarising the evidence it may be said that the com- 
pound Cu,Zn, certainly exists and can melt without decom- 
position. A compound CuSn also probably exists which is 
strongly dissociated at high temperatures and to a marked 
degree at lower temperatures, giving rise to copper and the 
compound Cu,Zn,, accompanied by the formation of mixed 
crystals with the components. 

Copper-calcium.—Copper is said to combine with calcium, 
forming the compounds Cu,Ca and CuCa,. The existence 


1 Zeit. anorg. Chem., 58, 28 (1907). 
2 Ber., 38, 2186 (1905). 

3 Ibid., 38, 2190 (1905). 

4 J. Phys. Chem., 11, 501 (1907). 


152 CHEMICAL COMBINATION AMONG METALS. 


of the latter compound is somewhat doubtful, as N. Baar! 
has shown in his study of the system. The diagram is given 
in Fig. 71. From the eutectic point the curve rises up to 
13-7 per cent. by weight of calctum, a maximum correspond- 
ing to the compound Cu,Ca, which melts at 933°. From 
this point to the next, eutectic crystals of Cu,Ca separate. 
From melts containing more than 38 per cent. of calcium, a 
series of mixed crystals separate whose last member contains 





12.00 





1100 





) 
a 


ys 








{000 


~ 


— fr eR 








~~ 








~ 
Sa 
ie 
Z 
EAN 
% 

















_—_— —~+- 
‘ 
sg 








1 









































o 
Cc 
1s] 
i A 
~~ we Se — we ~~ & ww eS LW 
s 
bh. 





Cc 
c 
oO 
a eran 
ae 


FIG. Way 


' 56 per cent. On the cooling curve of alloys between 23-5 and 
90 per cent. calcium, points of arrest are noted at 480° with 
a maximum for 70 per cent. of the metal. This alloy, which 
may be a mixed crystal or the compound CuCa,, has a homo- 
geneous appearance and passes without change of composi- 
tion from an a to a B form. 

Alloys containing about -8 per cent. calcium are not acted 
upon by water and are copper-coloured, those with 1:25 per 
cent. of calcium are a little harder than the pure metal. The 
others are more brittle, decompose water, and decompose in 


' Zeit. anorg. Chem., 70, 532 (1911). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 158 


air to a powder, which up to 35 per cent. calcium has a brassy 
colour. From 35 per cent. upwards of calcium the alloys are 
silvery white when freshly prepared, but decompose when 
exposed to the air. 

Copper-cadmium.—Copper forms two compounds with 








900" De 


. Cd Col: . S 
6004 | Xs 
oS 
as 
: N\ 























5004 2 | SY ee oN 


SQQVV“ Cu : Ca 
== - 


aa x ¢ Cu, Ce Cu 



























































(@) 10 20 40 L0 So 60 1O go 90 400 


Fie... 723 


cadmium, namely: Cu,Cd and Cu,Cd,. The diagram 
(Fig. 72) has been drawn from thermal data by Sahmen.? 
From melts containing up to 42 per cent. cadmium, pure 
copper separates out at temperatures between 1084° and 552°. 
At 552°, copper, reacting with the melt, forms a compound 
crystallising in long needles. The eutectic horizontal is 
prolonged to alloys richer in copper, and ends at 33 per cent. 


' Zeit. anorg. Chem., 49, 301 (1906). 


154 CHEMICAL COMBINATION AMONG METALS. 


cadmium, rendering almost certain the existence of the com- 
pound Cu,Cd. This compound was cbtained in crystals by 
Myhus and Fromm! by precipitating a 1 per cent. solution 
of copper sulphate with cadmium. A slightly defined 
maximum 1s observed on the fusion curve, corresponding to | 
the second compound. On both sides of the maximum 
mixed crystals are formed, on the one side between Cu,Cd, 
and Cu,Cd and, on the other, between Cu,Cd, and cadmium. 
Sahmen believes this formula to be more probably correct 
than Cu,Cd;.. The alloys richer in cadmium are soft ; with 
decreasing content of this metal they become more hard and 
brittle, but the brittleness decreases on further increase of the 
copper content. Alloys containing up to 40 per cent. copper 
are grey, but with increase of copper they become more 
reddish until the copper colour is reached. 

Copper-mercury.—The copper amalgams have not as yet 
been studied thermally. Chemical and physico-chemical 
researches on these alloys are, however, numerous.” The 
researches of J. Joule? and E. De Souza? on the capacity 
for chemical combination of the two metals should be 
recorded. The former obtained from liquid amalgams well- 
defined crystals corresponding to the formula HgCu. The 
existence of Hg,Cu; is doubtful, a solution of copper in 
HgCu having probably been mistaken for it. According to 
De Souza the compounds HgCu,, and HgCu,,; are formed. 
Copper amalgams on account of their plasticity are frequently 
used for technical purposes. 

Copper-aluminium.—Copper forms with aluminium the 
three compounds Cu,Al, CuAl, and CuAl,. The copper- 
aluminium alloys have been frequently studied by various 


1 Ber., 27, I., 630 (1894). 

2 Regnault, C. R., 52, 533 (1861). Becquerel, ibid., 75, 1729 (1872). Merz and 
Weith, Ber., 14, 1438 (1881). Battelli, Rend. Acc. Lincei, (4), 3, I1., 37; 4, 206 (1887). 
Bachmetieff, J ahrber., 109 (1893). Gouy, Jour. de Phys., (3), 4, 320 (1895). Humphrey, 
J.C. 8S., 69, 343 (1896). Coehn, Zeit. phys. Chem., 38, 609 (1901). Haber, ibid., 41, 
399 (1902). 

Sod CWS, 16, 18 41803): 

4 Ber., 9, 1050 (1876). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 155 


ov 


workers. We may mention the investigations of Le 


Chatelier,t Campbell and Mathews,? Guillet,’ Carpenter and 


aioo?® 



































































































































$0 5 % 
1000° 
$o 
900° x 
50 \ | 
5 
uAl, | Cx 
800° 
50 | 
; | et 
: 8 
200 
> 
x 
50 ee eae tee 
4 
600° WKY 2 
YN KS 
Ha. 
ae LE LLG ATS Sas are 
, ' 
! 
s00°|! 
(o) 10 20 50 ve) TO Jo 100 





mx CA ORG CAE Ck 


Figq@. 73. 


Kidwards,* Curry ° and, above all, the recent work of Gwyer °® 
in Tammann’s laboratory at G6ttingen. 


1 Bull. Soc. d’ Encour., (4), 10, 573 (1895). 

2 J. Am. C. S., 24, 253 (1902) ; 26, 1290 (1904). 

3 Rev. de Métallurgie, 568 (1905). C. R., 14, 464 (1905). 
4 Proc. Inst. Mech., 57 (1907). 

5 J. phys. Chem., 11, 425 (1907). 

6 Zeit. anorg. Chem., 57, 113 (1908). 


156 CHEMICAL COMBINATION AMONG METALS. 


Gwyer’s diagram is shown in Fig. 73, as being that of 
createst interest. It shows a maximum, two discontinuities 
and an eutectic point. The maximum at 1050° and 75 per 
cent. copper corresponds to the compound Cu,Al. There 
exists in all probability a gap in miscibility between 91:5 
and 88-5 per cent. of copper ; the corre ponding alloys show 
two species of crystals, one of primary separation surrounded 
by crystals of the other species. Between 88-5 per cent. and 
71 per cent. of copper there is a series of mixed crystals, 
varying in colour from golden yellow to silvery white. At 
625° the saturated mixed crystals react with the melt form- 
ing the compound CuAl at a concentration of 50 per cent. 
At 590° and about 34 per cent. copper the compound CuAl, 
separates from the melt and the compound CuAl. 

Copper-tin.—The system copper-tin has been investigated 
by Stanfield,| Heycock and Neville? Roberts-Austen,? 
Shepherd and Blough,’ and Giolitti and Tavanti.2 The two 
metals combine to form the compound Cu,Sn. Fig. 74 gives 
the diagram constructed by Giolitti and Tavanti from 
thermal data. It may be divided into two parts, the 
division being given by the compound Cus;5n which corre- 
sponds to 25 per cent. of tin. According to the other 
authors, the crystallisation of a homogeneous body should not 
take place but an interval of crystallisation should occur. 
The first part of the diagram, then, extends over the alloys 
containing up to 25 per cent. of tin. Here solidification 
begins at points on the line y @ a, which is made up of three 
separate branches on which solid solutions occur. The alloy 
of composition corresponding to the compound behaves as a 
single, chemically definite substance showing a homogeneous 
structure when viewed microscopically. The addition to 
the compound of a small quantity of tin lowers its solidifica- 


1 Proc. Inst. Mech. Eng., 269 (1895). 

2 Phil. Trans., 189 (1897) ; 202 (1903). 
3 Proc. Inst. Mech. Eng., 67 (1897). 

4 J. phys. Chem., 10, 630 (1906). 

5 Gazz. Chim. Ital., 38, TI., 209 (1908). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 157 


tion point. Alloys containing more tin than the compound 
give solid solutions between the compound and tin. There 
is an eutectic between the compound and tin; other authors 
place it somewhat nearer to pure tin. Between about 53 per 
cent. and 72 per cent. of copper, Shepherd and Blough 


AAoo® 





4000° 





900° 














700° 








600° 








500° 



















































































Si i by 
r Cu,|Sn ee 


ss = i 
10 20 40 Lo 50 60 %O gO 2:0 100 
aw Aton Cu 








Fra. a4: 


observed further transformations without, however, succeed- 
ing in elucidating their nature. 

The discussion of the particular regions of existence on the 
diagram of the system with regard to the formation of 
isomorphous mixtures would occupy too much space and 
would not be useful for the present work; the problem 
cannot indeed be regarded as completely solved. 


158 CHEMICAL COMBINATION AMONG METALS. 


Copper-antimony.—Copper forms with antimony the two 
compounds Cu,Sb and Cu,Sb, of which the latter agrees with 
the saline valency of monovalent copper. The system has 
been studied by Baikoff,! Hjorns,? and Parravano and 
Vivian.’ It is not certain at what concentration antimony 


o 
4400 





f 





Cu, 5S 





800° 


| 
| 
» |g PeaeINS YY 




































































600° ae N + 
D SST ! 
Waar N | | 
Z LZ -_—" . N fp | le 
ghar lst : eh Sele ee 
| . an 
a 8 | t 
400° x ‘ ea, ~-+ so} ---- 4 
t ~ ee SS 
| 
l pe +! Cu, SB Care : 
300° | Z ‘ | 
Cu, 58 
| 
| 
| 
‘200° { rt 
0 40 10 40 ho 50 GO %o rae) go 400 





Fig, 75. 


dissolves in copper ; Parravano and Viviani contend that the 

amount of such solution is neglgible. The compound 

CusSb (see Fig. 75) is indicated by a maximum at 682° and 

25 per cent. of antimony. It forms solid solutions with 

antimony and with excess of copper, and undergoes a trans- 

formation at 407°. According to Baikoff there is at 390° in 
Bull. Soc. d’ Encour., I., 626 (1903). 


1 
2 J. S.C. Ind., 25, 616 (1906). 
3 Gazz. Chim. Ital., 40, II., 446 (1910), 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 159 


this region a dystectic point for 23 per cent. of antimony. 
However, as Guertler' observes, the phenomena in this region 
are not clearly defined. The other compound, for which, 
however, there are not reliable data, would appear to 
separate at 587° and 83-3 per cent. of antimony. It is 
uncertain whether solid solutions exist between antimony 
and copper. Parravano and Vivian hold that in every case 
they are formed to a limited extent. Hjorns has argued 
their existence from the occurrence of brown spots in 
crystals of antimony. Guertler, however, is of opinion that 
such spots are due to local oxidation. 


COMPOUNDS OF SILVER. 


Salver-magnesium. — Silver combines with magnesium, 
forming two compounds, AgMg and AgMgs. The system 
has been studied by Zemezuzny,? and the diagram is shown in 
Fig. 76. Boudouard ? had previously reported the existence 
of three compounds, AgMg,, AgMg and Ag,Mg. A distinct 
maximum is seen on the diagram, corresponding to the com- 
pound AgMg; there is a transformation point for the com- 
pound AgMg, and two eutectic points. At 466°, at a con- 
centration of 17-3 per cent. silver, the alloy which solidifies 
is an eutectic mixture of magnesium and the compound 
AgMg,. An arrest is noted without any maximum corre- 
sponding to the compound AgMgs, which melts with decom- 
position at 492° and 22-5 per cent. of silver. At about 820° 
and 50 per cent., the compound AgMg separates ; on both 
sides of it solid solutions are formed. ‘This might lead to the 
supposition that we are here dealing with one of the types of 
solid solution laid down by Roozeboom. In Roozeboom’s 
types, however, the solid solution series are uninterrupted, 
while here there are gaps in the series. An analogous case 
has been brought to light by Baikoff* in the fusion of the 

1 Métallographie, Vol. I., Part I., p. 756. 
2 Zeit. anorg. Chem., 49, 400 (1906). 


3 Bull. Soc. d Encour., 200 (1903). 
# Journal of the Russian physico-chemical Society, 36, 111 (1904). 


160 CHEMICAL COMBINATION AMONG METALS. 


copper-antimony alloys. These alloys are very hard, and 
become increasingly so as they approach in composition to 
the definite compounds. They vary in colour from white 
(in the case of almost pure silver) to yellow. Alloys rich in 
magnesium are very brittle and decompose water more 
readily than pure magnesium. They are oxidised to a 
black powder on exposure to air. 






















































































AAco 
“TgGAg 
4000" 
Mg, A | 
900°| - 93019 
y: 6 
8004 | eee Ses Yo, Po 
o Danton 
7004 | x . 
: Ax ai 
C00 Up S RES 
4 x y 
: A Z 
500° a 4 ise £ 
GAGS <a . 
i ra CxS 
Zoo? 5 Ow 
200°L__“la, Ag Ly, Ag 
S 10 Wega 0 +O 50 GOls a eae Jo 90 100 
—@$———> 2 oui Ag 


FIG. 76. 

Silver-calcitum.—tThis system was studied by Baar,’ who 
observed the formation of the following compounds : 
Ag,Ca, Ag,Ca, Ag,Ca, AgCa and AgCa,. On the fusion 
diagram (see Fig. 77), there separates at C an eutectic 
conglomerate of crystals of silver and the compound Ag,Ca. 
At 20 per cent. of calcium and 650°, the compound Ag,Ca is 
formed. At 688°, crystals of Ag,Ca separate which coexist 
with the melt. At 25 per cent. and 725°, crystals of Ag3Ca 

t Zeit. anorg. Chem., 70, 352 (1911). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 161 


are in equilibrium with a melt of the same composition. A 
further addition of calcium gives rise to a discontinuity at a 
point which corresponds to the compound Ag,Ca,at 596° and 
33-5 per cent. calclum. From the eutectic point H the curve 
rises, Indicating a new crystalline species ; the maximum at 
50 per cent. and 665° is due to the compound AgCa. The 
curve then falls to 70-5 per cent., separating mixed crystals. 
From 54 yer cent. to 64 per cent. of calcium, arrest points 
occur corresponding to the formation of the compound AgCag. 



















































































1100 
100 0;—=—— a 
A 
Yoo gala 
rqta 
Aq a | 8 
goa A é , 7S 
be \ F J: ig Agla, \ 
4oo a D«< | Kk S| -- 
ee LAN : EN RYO 
600 Dl } sig Na Se M SRN 
: ats ») = ee et 
Slo aaa ANN 
foo f T a 
tie cheese pap as eB ae 
Lov | : % 
' ee i 
Pepi e Et 
coos me 20 40 4O so (exe) to 90 so 1900- 
see) 3 Gn. Eee Ca ; 
Fia. 77. 


The silver-calcium alloys are not so ductile as silver. They 
are increasingly brittle up to 86 per cent. of calcium, whence 
their brittleness decreases. Up to 86 per cent. of calcium 
these alloys are unattacked by water, but with more calcium 
they react with water and are oxidised in the air to a grey 
powder. 

Silver-zinc.—Silver forms numerous compounds with zinc. 
They comprise Ag,Zn,, AgZn, Ag,Zn, and Ag,Zn;, in which 
the saline valency of the two metals is not exhibited at all. 
The system silver-zinc studied by Gautier! and Heycock 


1 Bull. Soc. @ Encour., 1315 (1896). 
C.-M. u 


162 CHEMICAL COMBINATION AMONG METALS. 


and Neville * has since been well worked out by Petrenko.? 
The diagram is given in Fig. 78. No maximum is shown, but 
five points of discontinuity, of which three, 8, y and 3, 
are evident and well defined by thermal horizontals; the 
other two are less clear. The compounds correspond with the 
various points of discontinuity. At 28-1 per cent.? zinc and 
710° there separates Ag,Zn,, at 37-7 per cent. and 694° 
AgZn, at 47-61 per cent. and 665° Ag,Zng, and at 60 per cent. 

























































































4000° 
> 
Ag|Zn 
900° ZA 
N 
: Ay, Zn, Ag, ae v4 
Ay, 6 
800° na ies NS 
S ie 
» ; 
COO NE ? & 20 5 @ 
ol i 
: J, Zn 
FS -S 
600° ; de 
- lor 
| 
500° A | 
N 
Pom 
600 ° ZL 
NZ 
300% | 
O 10 2:0 30 40 70 GO #O g 0 30 400 


Fig. 78. | 


and 638° Ag,Zn;. The crystalline conglomerates consist 
alternately of homogeneous mixed crystals and of the two 
structural elements. 

Alloys rich in zine are harder than alloys containing smaller 
proportions of this metal; the maximum hardness occurs 
between 47-6 and 60 per cent. of zinc. The colour of alloys 
varies from silvery white to bluish grey. 


1 J.C. 8., 71, 407 (1897). 
2 Zeit. anorg. Chem., 48, 347 (1906). 
* The percentages here are percentayes by weight, not atomic percentages. 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 1638 


Silver-cadmium.—dilver combines with cadmium, forming 
the compounds AgCd,, AgCd,, Ag,Cd, and AgCd. The 
system has been investigated by Gautier,t Kirke Rose,? 
Bruni and Quercigh,®? and Petrenko and Ieodoroff.4 The 
diagram is given in Fig. 79. Silver and cadmium mix in all 
proportions in the fluid state ; i the solid state they form a 
series of solid solutions. At 200° and about 50 per cent. the 
compound AgCd 1s formed. On the cooling curve between 
500° and 600°, are two arrests which, although there are no 
transformation points, may represent the compounds AeCd, 
and AgCds, the latter being admitted by Maey from his 
determinations of specific volume. At the point Ff’, at about 
30 per cent. silver and 630°, there separates the compound 
Ag,Cds, of a rose colour and very brittle. The mixed crystals 
g and g, which are formed at 57 per cent. and 64 per cent. 
respectively of silver, are very near to the compounds 
Ag,Cd, (59:02 per cent. Ag) and Ag,Cd (65-7 per cent. Ag) 
reported by Kirke Rose. The composition of the saturated 
mixed crystals g’ changes with fall of temperature, while 
the crystals g retain constant composition. 

_ Salver-mercurya—Amalgams of silver, such as arguerite, 

crystallising in the regular system, are found innature. The 
formation of chemical compounds between the two metals is 
certain, although the system has not as yet been studied by 
methods of thermal analysis. 

Silver dissolves easily in mercury at boiling temperature, 
and from the solution may be obtaimed beautiful needle- 
shaped crystals known as “ Diana’s tree.’’ Numerous 
researches have been made to establish the existence of 


chemical compounds in silver amalgams.’ The existence of 


1 Bull. Soc. @ Encour., (5), I., 13815 (1896). 

2 Proc. Roy. Soc., 74, 218 (1908). 

3 Zeit. anorg, Chem., 68, 198 (1910). 

4 [bid., 70, 257; 71, 215 (1911). 

5 Bottger, J. Pr. Chem., 3, 278 (1834) ; Croockewit, Ann. Chem., 68, 289 (1848) ; 
Joule, Rep. Brit. Ass., II., 55 (1850); Rammelsberg, Pogy. Ann., 120, 54 (1863) ; 
Becquerel, C. R., 75, 1729 (1872): De Sousa, Ber., 8, 1616 (1875) ; Merz and Weith, 
Ber., 14, 1438 (1881) ; Schumann, Wied. Ann., 48, 101 (1891) ; Gouy, J. de Phys., (3), 4, 
320 (1895); Littleton, J. C. S., 67, 239 (1895) ; Berthelot, C. R., 182, 241, 290 (1901) ; 
Ann. Chim. Phys., (7), 22, 317 (1901) ; Coehn, Zeit. phys. Chem., 38, 609 (1901). 

1l—2 


164 CHEMICAL COMBINATION AMONG METALS. 


the compounds HgAg,, HgAg and Hg,Ag, is probable. An 
amalgam of the composition Hg,Ag, in well-defined crystals 


10 20 30 40 30 60 VO 80 30 100 


















































Ca | 1A 
Led VA 
900 Wi 
SOO Wa os 
La € 
S| fee 
¥00 c las 
BE Gees se a 
5 ee S LZ7¥; ! 
V7 
COO S FE ele ’ H 
SOT I al ive 
Ne Bo. aed ; a . 
50 et 
C / ]b 1% \ ] 
ba 1 
A ae Z 
400 ! | 
i Pte lee, 
AL’ , i tte 
FOO a 
7 |\QtO ! 
l ' 
ies 
200 i aa 
! ' 
ie. halted | 
| | pedotee 
zoo | le _AO| gO '40 50 60 70 80 IY 1% 















































Fie. 79. 
was isolated by Dumas.! Ogg ? prepared various amalgams 


of silver by electrolytic methods. 


1 (. R., 69, 759 (1869). 
2 Zeit. phys. Chem., 27, 301 (1898). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 165 


Silver-alumanvwm.—Aluminium and silver form the com- 
pounds Ag,Al and Ag;Al, the latter of which exhibits the 
saline valency of the two elements. Fig. 80 is the diagram 
constructed by Petrenko? from thermal data. The pre- 








1000“ ; 
i 
D 
Pe fi 
wo0. AY 








x ; Ag, AL Gs | 
800° | 

NS 

4¥) 

‘a 

B 
















































































x 
50 2 be 
ue 
200° ‘< 3 p 
i> SS CT 
boot Li a Low < em 
LL POP 2 Pm LISS | 
a —— 2 
— 
oe ae ee 
o 10 QU $0 Eb. 8 250 60 0S" 80 90 400 


J, ~ Corum ody 





Fig. 80. 


ceding investigations of Gautier,’ Guillet,? and Heycock and 
Neville * may also be mentioned. The diagram shows that 
the two compounds mentioned above are formed. The 
cooling curves of the compounds are similar in character to 
those for other simple substances, showing only single arrest 
1 Zeit. anorg. Chem., 486, 49 (1905). 
2 Bull. Soc. d@ Encour., 1312 (1896). 


3 Génie Civil, 1902. 
* Phil. Trans., A, 69 (1897). 


166 CHEMICAL COMBINATION AMONG METALS. 


points. ‘The interval of eutectic crystallisation at 567° is for 
the first compound reduced to zero at the point 8, while for 
the second compound at 75 per cent. silver and 770°, the 
interval is greater than for all other melts. Transformation 
points are shown at 718° and 610° respectively. These 
alloys consist in section of a single species of crystals. 


1000° 


- 900° ae ve 
7 
| 








800° 













































































out oe EE SN f 
. Ss 
400° ; SISA 8 ; 
IERRN SONY 
"FAQS 
ae On |t & oe Sn 
O 10 20 80 40 50 GO 40 $0 36 10D 


J, im Qloun Ag 





Fre. 81. 


The two alloys form mixed crystals between 610° and 718°. 
It is uncertain whether the transformation of mixed crystals 
takes place with or without separation of their components, 
AlAg, and AlAg,. On the curve above 718° £6 crystals of 
AlAg, are in equilibrium with the melt, while below 718°, y 
crystals are similarly in equilibrium. ‘The presence of this 
branch indicating the equilibria of the y crystals cannot, 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 167 


however, be demonstrated directly. A horizontal indicates 
the transformation of 6 into a crystals. 

Microscopic examination confirms the foregoing deduc- 
tions, since it reveals the presence of the five groups of alloys 
which are presumed to exist from thermal considerations. 

Salver-tin.—Silver forms the compound Ag,Sn with tin as 
may be gathered from Fig. 81, which reproduces the diagram 
constructed by Petrenko! from thermal data. Heycock and 
Neville ? had previously studied the system. There are two 
branches on Petrenko’s diagram, the one straight and the 
other sinuous; at 480°, 232° and 220° respectively, horizontals 
occur. At 480° and 27 per cent. of tin, the compound Ag,Sn 
separates. Microscopic examination shows that the alloy of 
this composition consists of polyhedra. The compound is 
dimorphic. A maximum interval of transformation occurs 
at 232° at a concentration corresponding to the compound. 

Silver-antimony.—Silver combines with antimony to form 
the compound Ag,Sb, as appears from the investigations of 
Gautier,? Heycock and Neville,* and, finally, of Petrenke.® 
Maey ° from volumetric observations argues that silver and 
antimony form a single compound Ag,Sb. Pushin,’ how- 
ever, from his measurements of electro-motive force, argues 
that there are two compounds, Ag,Sb and Ag,Sb. 

Petrenko’s diagram, shown in Fig. 82, demonstrates that 
by addition of antimony the melting point of silver is 
lowered sharply. Mixed crystals containing antimony 
separate, which are recognisable by microscopic examina- 
tion. At 560° and 27-07 per cent. of antimony, there is a 
sharp arrest point corresponding to the compound Ag,Sb. 
From 27:07 to 45 per cent. antimony the compound 
separates and at 485°, the eutectic alloy. Microscopic 

1 Zeit. anorg. Chem., 58, 200 (1907). 

2 Phil. Trans., 189, A, 140 (1897) 

3 Bull. Soc. d Encour., 1896, pp. 1309, 1310. 
4 Phil. Trans., 189, A, 25 (1897). 

5 Zeit. anorg. Chem., 50, 139 (1906). 


6 Zeit. phys. Chem., 50 (1905). 
7 Journ, Russ. phys. Chem, Soc., May, 1905. 


168 CHEMICAL COMBINATION AMONG METALS. 


examination confirms these data. he compound appears 
in polygonal crystals separated by fine lines. 
Silver-manganese.—It is not certain whether silver forms 
compounds with manganese. The system was studied by 
thermal and miscroscopic methods by Hindrichs! and 
Arrivaut?; the latter also used chemical methods and 
determined electrolytic potentials. Hindrichs does not 


1000° 





900° 





Ag, Sb 


[4 

800° ky 
| & 
700 ay 

\ 

600° of\\! 
















































































YZ: | 
; S| 
500° oy W/V ro 

EL EES EES SEE BP EY A BEY AY SE 

ieee ee 

400° Bae S Ags 5b 
300° 

oO 10 20 30 Lo SC 60 20 sO 4:00 


gO 
5 7, OAM aA lg 





Fig, 82, 


report the formation of compounds, but states that two 
strata exist with limited mutual ‘solubility. Arrivaut, 
while admitting the limited miscibility of the two metals, 
maintains that at 978° and at 20 per cent. of man- 
ganese, the compound Ag,Mn is formed. The compound 
forms a contimuous series of mixed crystals with silver. 
Guertler,* however, is of opinion that the supposed com- 
pound is, rather, a saturated solution of manganese in silver. 
1 Zeit. anorg. Chem., 59, 437 (1908). 


2 Thid., 83, 193 (1913). 
* Metallographie, Berlin, 1912, Vol. I., Part I., p. 98. 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 169 


By analogy with gold, the existence of a combination between 
silver and manganese is probable. 

Sulver-platinwm.—There is some doubt as to the occur- 
rence of chemical combination between silver and platinum. 
According to Doerinckel’s! investigations, the compound 
Ag,Pt is formed between the two metals. Thompson and 


D 





1800° 


ras 


f 


1700° 





| SSS“ 


o 
[ 
K 
! 

T 
\ 
| 
KI 
| 


1600" 





1500° 














SNS 
WSS 
SN 








feat 
S 
_N 
N 

> 
e 


~ 
NN 
aS 
AN 
SS 





! 


Saas 
( 
{ 
‘lint 
| 
LdgN 
| 
























































0: 10 10 30 LO SG G0 40 TG Tae TOG 
Ds a2 IES nce Ug 
Fig. 83. 


Miller? stated that such a compound was formed and noted 
that platinum, when alloyed with silver, was soluble in nitric 
acid. Fig. 83 is Doerinckel’s diagram. It cannot be drawn 
above 80 per cent. platinum on account of the high melting 
point of such alloys. At 1184° and 20 per cent. platinum 
there is a distinct discontinuity. Up to 35 per cent. there 
is a continuous series of mixed crystals, the last member of 


1 Zeit. anorg. Chem., 54, 338 (1907). 
2 J. Amer. C. S., 28, 1115 (1906). 


170 CHEMICAL COMBINATION AMONG METALS. 


which contains 48 per cent. by weight of platmum. This 
corresponds fairly nearly to the formula Ag,Pt, which would 
require 47-5 per cent. of platinum. It is doubtful, however, 
whether this is a compound or mixed crystal. 

The alloys from 10 to 30 per cent. are a little harder than 
their components. From 40 per cent. of platinum the hard- 
ness increases slowly and at 70 per cent. exceeds that of 
cale spar. 


COMPOUNDS OF GOLD. 
Gold-magnesium.—Magnesium forms four compounds with 





1200¢ 


1100 
































0 1 2 30 40 50 60 % 60 90 Wo 
Fiq, 84. 


gold, in none of which saline valencies are shown. They are 

AuMg, AuMg,, AuMg, and Au,Mg,;. The system has been 

studied by Vogel,! by Urasoff? and by these two authors in 

collaboration.2 The results obtained are in general agree- 

ment (see Fig. 84). Vogel admits the first three. compounds, 
| 1 Zeit. anorg. Chem., 63, 169 (1909). 


2 Tbid., 64, 375 (1909). 
8 [bid., 87, 442 (1910). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 171 


while Urasoff adds Au,Mg, which would appear to separate 
at 796° and 72 per cent. of magnesium. For the first three 
compounds, whose concentrations are respectively 50, 67 and 
75 per cent. of magnesium, Vogel gives the melting points as 
1160°, 796° and 880°, while Urasoff gives 1150°, 788° and 818°. 
Between 80 and 384 per cent. of magnesium Vogel has 
observed that although the alloys at 830° are homogeneous, 
when cooled slowly to 818°, they separate out crystals, 
which would show a diminution in the solubility of the 
alloys from 0 to 30 per cent. in the foregoing alloys. At 
720° and 72 per cent. of magnesium, Urasoff observed a 
thermal effect due to a transformation of the compound 
Au,Mg,. 

Gold forms solid solutions with magnesium from 17 to 27 
per cent. magnesium ; magnesium in the crystalline state 
does not dissolve notable quantities of gold. 

Gold-zinc.—Gold and zine form the following compounds : 
AuZn, Au,Zn, and AuZn;. The system was studied by 
Vogel } and the diagram is shown in Fig. 85. At 50 per cent. 
zinc and 744° there is a maximum corresponding to the com- 
pound AuZn which, by reaction with the meit, gives mixed 
crystals with gold and zinc. Between 50 and 63 per cent. of 
zinc, mixed crystals separate with a higher content of zinc 
than is demanded by the formula AuZn, and at about 650°, a 
homogeneous substance crystallises which is the compound 
of the formula Au,Zn,;. At 486° saturated mixed crystals y 
are changed into a third compound. The maximal trans- 
formation is at 88 per cent. of zinc corresponding to the 
formula AuZn,;. Here a new series of mixed crystals occurs. 
Alloys rich in gold have the same hardness as that metal, are 
less tenacious, and not at all brittle. At above 31 per cent. 
of zinc the alloys show considerable hardness and brittleness. 
After 61 per cent. they become gradually less hard and 
brittle. 

Gold-cadmium.—Gold forms two compounds with cad- 


1 Zeit. anorg. Chem., 48, 319 (1906). 


172 CHEMICAL COMBINATION AMONG METALS. 


mium, Au,Cd,; and AuCd,; as shown by Vogel, who has 
constructed the diagram shown in Fig. 86 from thermal data. 
The crystallisation of the two compounds is marked by two 
distinct discontinuities, one at 45 per cent. cadmium and 
623°, and the other at 75 per cent. cadmium and 493°. From 
0 to 28 per cent. cadmium, a series of mixed crystals is 
formed. Au,Cd, forms with the saturated mixed crystal 8, 
occurring at 51 per cent. cadmium, a series of mixed crystals 


1100° | 


A ree op rm q 
1000° A 


Au,2n 

















aes 
_— 
SN 
a 





8 
700° | vo 







































































| S 
600° aN y, 
s i oa mi 

500° > + 

ee: ae RATA i 3 

lf ANS f ss 
400°) Jf B 

Oo ae. 20 30 LO 50 GO XO gO 90° 400 

an Clone 24 a 
Fia@. 85. 


rich in cadmium, while AuCdy crystallises in eutectic alloy 
from melts rich in cadmium. The compound AuCd, whose 
formation was reported by Heycock and Neville,2 might be, 
according to Vogel, a mixed crystal containing Au,Cd, of the 
f series, richer in cadmium, and only having the composition 
corresponding to AuCd fortuitously. The more recent studies 
on the gold-cadmium alloys made by Saldau ® have regard 
to thermal phenomena, hardness, the special properties of 
1 Zeit. anorg. Chem., 48, 333 (1906). 


2 J.C. S.. 61, 888 (1892). 
3 Int. Zeit. f. Metallogr., VII, 3 (1914). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 178 


eutectic alloys, electrolytic potential and microscopic struc- 
ture. Saldau, from his investigations, maintains that these 
alloys include the compounds AuCd and AuCd,. He derives 
the former not only from the fusion diagram, but also from 
the diagrams for hardness and electrical conductivity. The 
first compound separates at 50 per cent. and about 625° and 


100° 


: > 
1000° 


900° 











600° 
















































































700° Au Cd & 
KS 
oe 
600° Qe’ dS | ee] 
Ue 
<& ot 
Poo: ALN 
Wr a 
400° pS 
RAN fe B 4 
Cd : 
NB 
300 , SS \ 16) 
| Au Cd, “i 
Au byt Cd 
200° 
re) 10 10 30 40 50 ae) #0 go 90 100 
By wn anes Aw 





Fig, 86, 


the second at 75 per cent. of cadmium and 490°. According 
to Saldau the compound stated by Vogel to be Au,Cd, has no 
real existence, for this concentration simply represents the 
limit of saturation of the compound AuCd with gold in 
mixed crystals. The two compounds form mixed crystals 
with the components, AuCd between 46 and 59 per cent. 
cadmium, and AuCd, between 74 and 79 per cent. cadmium. 
Two other series of mixed crystals exist, one between gold 


174 CHEMICAL COMBINATION AMONG METALS. 


and cadmium up to 35 per cent. of cadmium, and the other 
between cadmium and gold up to 2 per cent. gold. 

The alloys show maximum hardness at 18 to 30 per cent. 
of cadmium and 51 to 63 per cent. cadmium ; the maximum 
brittleness occurs at 51 to 63 per cent. cadmium. 

Gold-mercury.—Gold amalgams occur naturally as solids 





1200° 
& “ Al lAu 2 


7100° 





_ 


1000° 





Al Aul, A 
= 
ae 
g00° AS 


TANSSSNUT FAS 
SMV TAS 

























































































. vial ij TO “OO "0. Ono : 
600° aa N ~ ~ 
WI) SY cS 
Heo o LA ih Ed nc a] : Sy ee \ 
= . ne ; 
500° = 
A < 
Al, Au Al Au | g@]AlAul Al | Au, 
400° + 
> ae + + 
All + Al,} Au A ul 
Al Au, es Al Au, A 
300° Peels All| Au 2 te 0 oes 2 
6 10 210 40 40 $0 60 40 vo 90 400 


SP ew OA ok 
Fig. 87, | 

or semi-solids according to their mercury content ; the solid 
amalgams are well crystallised. | 

The two metals combine chemically, but the system hag 
not yet been studied thermally. Béttger! prepared arti- 
ficial amalgams by direct union of the two elements. 
Croockewit* isolated a compound of the formula AuHg,. 


1 Jour. pr. Chem., 8, 278 (1834). 
2 Ibid., 45, 87 (1847). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 175 


The numerous investigations ! on these amalgams lead us to 
suppose the existence of other combinations richer in gold. 
The existence of the compounds Au,Hg and Au,Hg seems 
probable. The goid amalgams have always been of great 
importance in the extraction of gold from its minerals. 

Gold-aluminvum.—tThe system gold-aluminium was studied 
by Heycock and Neville’ thermally and micrographically. 
The two metals form the compounds Au,Al, Au,Al,, Au,Al, 
AuAl, AuAl,.. The curve shows two distinct maxima, one 
at about 1060° and 33:3 per cent. gold and the other at about 
625° and 66 per cent. of gold, corresponding te the com- 
pounds AuAl, and Au,Al respectively. There are three dis- 
continuities at which the other compounds separate. The 
first occurs at about 56 per cent. of gold and 625° ; probably 
it corresponds to the compound AuAl. Heycock and 
Neville noticed, however, that there is not a perfect equili- 
brium between AuAl, and the eutectic at 569°, for on 
microscopical examination they detected the presence of 
AuAl, characterised by its purple colour. The compound 
AuAl, indeed, does not separate in a pure state. The 
eutectic horizontal at 569°, which should only extend to 50 
per cent. of gold, reaches 40 per cent., which is explained by 
the fact that at that point the equilibrium is complete. The 
other two compounds Au;Al, and Au,Al separate respec- 
tively at 575° and 72 per cent. of go!d and 545° and 78-5 per 
cent. god. 

Gold-tun.—The following compounds are formed between 
gold and tin: AuSn, AuSn, and AuSn,. They have been 
recognised by Vogel ? by means of thermal analysis. Fig. 88 
represents the equilibrium diagram. Preceding Vogel’s 
work, the system had been studied from the point of view of 

1 Henry, Phil. Mag., (4), 9, 458 (1855) ; Knafel, Dingl. Poly. Journ., 168, 282 (1863) ; 
Rammelsberg, Pogg. Ann., 120, 54 (1863); De Souza, Ber., 9. 1050 (1876) ; Chester 
Ann. Jour. Sci., (3), 16, 29 (1878) ; Kasauzeff, Bull. Soc. Chim., (2), 30, 20 (1878) ; Merz 
and Weith, Ber., 14, 1438 (1881); Wilm., Zezt. anorg. Chem., 4, 325 (1893); Gouy, _ 
Jour. de Phys., (3), 4, 320 (1895). 


2 Phil. Trans., A, 194, 201 (1900). 
3 Zeit. anorg. Chem., 43, 69 (1905). 


176 CHEMICAL COMBINATION AMONG METALS. 


electrical conductivity by Matthiessen, while Maey ? and 
Heycock and Neville? studied the specific volume, and 
Lawrie * the electrolytic potential. The fusion curve falls 
from the melting point of pure gold to an eutectic point, and 






















































































Cc B 
1100° 
1000° oe a ee 
900° Sues 
800° 
700° 
° Au Sn 
OUR j aoe Au} Sn 
500° Au | Sn 4 | 
400° Be 3 ee gon 
WH» |S 
+ A 
300° 5 Ao 2 id, T Ws Wi ef Sy 
ae” : Sok. CEG < 
in os 7/1 /) oD, ee 
200" a ie ae Au Sn 
Au Sn + U Sn ree ¢ 
ee et ry. ihe fs 
100° Sn+ [Au Sn, | Av Sn 











0 10 20 30 40 ,90 60 70 ; 80 99 104 
se ESS oy Re OT mur me Lge 


Fia. 88, 


subsequently rises to a distinct maximum. In the rest of 
the curve two discontinuities occur which are met by 
thermal horizontals from 10 to 33 per cent. and from 30 to 50. 
per cent. respectively. From melts rich in gold, mixed 
crystals separate containing up to 8 per cent. of tin. The 


1 Pogg. Ann., 110, 190 (1860); Phil. Trans., 150, 161 (1860). 
2 Zeit. phys. Chem., 38, 292 (1901). 

3 J.C.8., 59, 936 (1891). 

* Phil. Mag., (5), 38, 94 (1892). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 177 - 


compound corresponding to the maximum has the formula 
AuSn and contains 37-63 per cent. by weight of tin ; it melts 
at 418°. At the temperature of the eutectic horizontal, 
crystals of AuSn react with the melt and pass into a com- 
pound richer in tin of the formula AuSn,, containing 54-68 





1100° 


1000° 





700° | tS 
VARS 


400° Sa Y 


Re 
eT 
‘Ewe 























4 
300° 







































































van ee} if 
ee £964 B Au Pb, + Aug Po 
200° 2a eam ore an Goad a7a am « eater ‘4 = 5 fs ee ect ; 
oe OE Sa 
Panes Au, Pb 
Poi +t | & |JAu Po, @ Au Pbh,+ Aul, Po 
100° ee 
O 105 AO 8 67 LO sO GO +O C0)» 90" AGO 
Fig. 89. 


per cent. by weight of tin and melting at 808°. This com- 

pound passes in turn into a third compound, AuSn,, which 

melts at 252°. All these alloys are very brittle and acid 

resistant, particularly the alloy AuSn, which is as brittle as 

class. | 

Gold-lead.—Lead and gold form the compounds Au,Pb 
12 


C.M. 


178 CHEMICAL COMBINATION AMONG METALS. 


and AuPb,. Vogel! has made a thermal study of this 
system. Maey’* concluded from a study of specific volumes 
that the compound Au,Pb, should also occur. 

The diagram is reproduced in Fig. 89. Two very distinct 
discontinuities are seen ; the first is at 418° and corresponds 


1100° 





~ 


1000° 





900° 





600° 








Vee 
os MAD — 





= IX 
\ 


600° 


3 
Nae A 
a SEN 
Mt trezk.| RX 
GS LU LEIA RING 
300° zi NI NN aa 
200° Shae 


a) 
fy) 10 20 “0 Lo 50 GOis2 S10. 80 90 400 
Ee EIS Nive © Bote Diy Pa 


Fie. 90. 



































ay 


> 

c 

ie 

ro 

bp 
7 

> 
c 















































to the compound Au,Pb with a maximal arrest for 35 per 
cent. lead. At 211° and the same concentration, a poly- 
morphic transformation takes place. The second discon- 
tinuity is at 254° and the corresponding thermal arrest, with 
a maximum at 67-8 per cent. of lead, indicates the compound 
AuPb,. This compound also undergoes a polymorphic 
transformation at 211°. The compound Au,Pb crystallises 


1 Zeit. anorg. Chem., 45, 11 (1905). 
2 Zeit. phys. Chem., 38, 292 (1901). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 179 


in large white crystals, AuPb, in long needles. The two 
compounds form mixed crystals with each other and with 
the components. 

Maey’s supposed compound Au,Pb, is explained by Vogel, 
who argues that the specific volume method can be used for 
alloys with two structural elements, but not for alloys such as 
those of this system between 10 to 72 per cent. lead having 
three such structural elements. Both compounds are 
brittle—Au,Pb more so than AuPb,. | 

Gold-antemony.—These metals according to Vogel! form 
the compound AuSb,. It is seen from the diagram (Fig. 90) 
that each metal lowers the melting point of the other. 
Primary separation of gold and antimony occurs at 0—84 
per cent. antimony and 73—100 per cent. antimony respec- 
tively. Melts containing 35 per cent. of gold separate the 
compound AuSb, at 460°. The primary separation of this 
compound continues till 84 per cent. of antimony is reached, 
when eutectic solidification occurs at a temperature of 860°. 
The compound AuSb, is harder than its constituents ; it is 
very brittle and more resistant than antimony to the action 
of acids. In section it has a shining shell-like crystalline 
appearance. 

Gold-manganese.—Manganese combines with gold to form 
the compound AuMn. This system was studied by Parra- 
vano and Perret.2, The capacity of gold for combination 
with manganese differentiates it from the first member of its 
group, namely, copper, which does not combine with man- 
ganese, but forms a continuous series of mixed crystals. In 
the case of silver, as mentioned above, its capacity for com- 
bination with manganese is not yet well established. In the 
fusion diagram (Fig. 91) described by Parravano and Perret, 
there is in addition to the formation of the compound 
AuMn, a lack of miscibility between 50 and 57-5 per cent. 
by weight of manganese. Further, transformations have 

1 Zeit. anorg. Chem., 50, 151 (1906). 


2 Gazz. Chim. Ital., 45, I., 298 (1915). 
12—2 


180 CHEMICAL COMBINATION AMONG METALS. 


been observed in the solid state which, however, are not 
yet well explained. Manganese lowers the melting point 
of gold to 990° for a concentration of 10-5 per cent. man- 
ganese. In this interval mixed crystals separate. There is 
a maximum at 1225° corresponding to the compound (21-8 
per cent. by weight manganese) ; thence the curve falls to 
1080° and 46 per cent. by weight of manganese. From this 
point the curve rises to the melting point of manganese, 
but between 50 and 57 per cent. of manganese a gap in 

















900 





Au 10 go 8a yp b0 jo yo «30 20 10 
—> % in peso. 
Fie. 91. 


liquid miscibility occurs. The formation of the compound 
has been confirmed by measurements of the hardness of 
alloys; the hardness curve of alloys up to 85 per cent. 
manganese is similar to the type represented in Fig. 34. 


Compounds of Metals of Group II. with Metals of 
other Groups. 7 


COMPOUNDS OF BERYLLIUM. 


Berylliwm-tron.—According to G. Oersheld,* the two metals 
combine chemically, and in all probability the compound 
1 Zeit, anorg. Chem., 97, 6 (1916). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 181 


FeBe, is produced. The system has been studied up to 21 
per cent. of beryllium. At 1155° and a concentration of 
38:4 per cent. (atomic) of beryllium, there is an eutectic point ; 
up to 29 per cent., solid solutions are formed. By addition 
of beryllium the transformation temperature of iron P into 
iron a is lowered till it becomes constant. The compound 
is blackened by alkalies. 


CoMPOUNDS OF MAGNESIUM. 


Magnesiwm-aluminnum. — Aluminium and magnesium 
form the compound Mg,Al,. The system has been studied 
by Boudouard! and Grube.? The diagram (Fig. 92), taken 


700; 








50 SS ‘ HN 


Y Als Mg, \ 
~ 


La | / N 
ZAZAZ ee INN 











( 


N\ 





a 
AY 
NN 


ve : 
¥ V7 ys \ 




































































° < 
400 ES —- \ S 
Vv . 
0 10 RO Se Saran ag 50 Cig ioe eae 90 409 
pane ene vie nay © Ol er a Abg 


Fi@q. 92. 


from Grube, is of interest because, although the compound 
has a range of existence of about 30 per cent., it displays no 
decided maximum ; this system approaches, therefore, to 
the type c described on p. 11. The maximum occurs at 


1 Bull. Soc. Chim., (3), 27, 5, 45 (1902). 
2 Zeit. anorg. Chem., 45, 225 (1905). 


182 CHEMICAL COMBINATION AMONG METALS. 


462-7° and 54-9 per cent. of magnesium. All the alloys from 
35 to 55 per cent. of magnesium crystallise as chemically 
homogeneous substances; they are in fact mixtures of 
Mg,Al, and excess of aluminium. 

The compound Mg,Al, has a silvery white colour and is 





650° 


600° 
50 4 


500°| — | nil, MQ N 
N 











400° és ASS 
PLS Sy Sea 
50 LSS 


150° L 
































200° 


















































Fig. 93, 


very brittle. The brittleness decreases from the composition 
of the compound to the two pure components. Alloys 
between 35 and 50 per cent. magnesium have, after polishing, 
a very bright mirror-like surface. 

The alloys of magnesium and aluminium are well known as 
“ magnalium.” 

Magnesium-thalluum. — Magnesium forms the following 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 1838 


compounds with thallium : Mg,Tl,, Mg.Tland Mg,T'l;. ‘The 
study of the system is due to Grube.t The diagram (Fig. 93) 
shows a distinct maximum corresponding to 27-4 per cent. 
thallium and two obscured maxima. Tor the latter, the 













































































-1000° 
1" 

900° 

800° ‘ 

700 FENN S 

a SASS Ne 
- NNN eee 
- ASRENS 

300 ve SANNA 
"IAS 

100° x ae ee ae. 

Cae 
Me 10 Ot aG Soc eo 6a on eo a 


Fiea 94. 


concentrations are 33°33 per cent. and 40 per cent. thallium 

respectively, corresponding to the compounds Mg,Tl and 

Mg,Tl,. The maximum, of course, represents the com- 

pound Mg,Tl,, which melts to a homogeneous liquid, 

while the other two break up on fusion into crystals of 

different composition and into melts. In the region on the 
1 Zeit. anorg. Chem., 46, 84 (1905). 


184 CHEMICAL COMBINATION AMONG METALS. 


diagram between the fusion curve and the eutectic hori- 
zontals there is equilibrium between one species of crystal 
and the melt. 

These alloys oxidise in air, particularly in a moist atmo- 
sphere; the compound Mg,TI though not very stable is 
slightly more resistant than the others. 

Magnesium-tin.—Magnesium and tin only form one com- 
pound, Mg,Sn. The system has been investigated by 
Grube! and Kurnakoff and Stepanoff.2 The diagram 
(Fig. 94) shows a maximum at 783-4° and a concentration of 
66:5 per cent. of magnesium ; this corresponds to the com- 
pound Mg,Sn. Below the fusion curve and above the 
eutectic horizontals there is in every region of the curve 
one species of crystals in equilibrium with the melt. The 
alloy Mg,Sn is formed with great development of heat ; it 
is brittle and has a steel blue colour which is tarnished on 
exposure by a stratum of black oxide. 

The diagram shows three groups of alloys: (1) alloys 
containing magnesium of primary separation; (2) alloys 
containing Mg,Sn of primary separation; and (8) alloys 
rich in tin containing tin of primary separation. 

Magnesvum-cervum.—V ogel,? who studied this system, has 
recorded the formation of four compounds, CeMg, CeMgs, 
CeMg, and Ce,Mg. His diagram is shown in Fig. 95. The 
two branches descending from A and C, along which cerium 
and the compound CeMg respectively separate, should 
apparently intersect in the point B. On the cooling curves 
of these alloys are noted two arrest points, one at about 632° 
and the other at 497° at a concentration of 20 per cent. 
magnesium. Vogel explains the presence of a compound 
here by assuming a decomposition to take place in the solid 
state. A small branch with a slight maximum at 20 per 
cent. should fill the gap between A and C. The compound 
CeMg separates at a concentration of 50 per cent. and 738°. 


1 Zeit. anorg. Chem., 46, 76 (1905). i? 
2 Ibid., 46, 177 (1905). 
3 Jbid., 91, 277 (1915). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 185 


The arrest point at 7, which practically occurs a little lower, 
corresponds with the separation of saturated mixed crystals 
containing magnesium. From melts with 60 to 75 per cent. 
—the latter bemg a maximum on the curve—the compound 
CeMg, separates at about 780°. Finally, at 90 per cent. of 
magnesium, the compound CeMgy separates. 

The compound Ce,Mg absorbs heat in its formation, 1.e., 
it is endothermic ; it has a very small field of existence and 








te, Mg Ce (Mts Le Mg 





~o 
iS 
6 

ay 

—— 











A 
: 

i)» meet S 
foo tf fe ~ : 



























































£ 
y, SN Q 
y WN { INNA 3g 
UH §§ SSSsy _ | SS « 
Goo a i == hy 
‘ 1 Mt 
| ! eee es 
00 —- 3 
400 L ! ae 
‘ ( 
{ 
ks : t 
| 
100 : ! | 
i ' 
| t 
| ¥. rl 
ae 0 10 Lo 30 pe 50 60 jo 0 go 108 


——_ vA m atonri Oe: 
Fig. 95. 


a low melting point. This compound, like all the alloys 
from 20 to about 62 per cent. of magnesium, ignites spon- 
taneously. The compound CeMg is very hard; a freshly 
broken surface shows a reddish grey colour. CeMg, is less 
~ hard than CeMg and is not so easily oxidised. CeMg, is 
brittle and has a silvery lustre when freshly broken. It is 
more resistant than the other compounds to oxidation and 
the action of acids. 

Magnesvwm-lead.—Lead forms with magnesium the com- 


186 CHEMICAL COMBINATION AMONG METALS. 


pound Mg,Pb, as was found by Grube! and Kurnakoff and 
Stepanoff.” The latter authors consider compounds of the 
type Mg.R (where R = Sn or Pb) as belonging to the hypo- 
thetical type RH, by replacement of four atoms of hydrogen 
by two atoms of bivalent magnesium. The curve (see 
Fig. 96) is similar to the curve for magnesium-tin. The 


K Se N 





to 
is) 








De, 
































WAZ Tal, 
yi 

































































ANA 
ANNI 
300° P> aA IN XS] 
SION om Se SI 
200 i eee 
100° a L— 
\ ra 
UZ 
is 40 20 30 LO 50 60 %O 30 90.. 100 


pe tO xe COLO AI Me 
Fig. 96. 


diagram consists of three parts ; in the first, lead separates ; 
in the third, magnesium ; while in the second, with a maxi- 
mum at 550° and 66-66 per cent. magnesium, the compound 
Mg.Pb separates. This compound is oxidised in moist air — 
and has a steel grey colour. 
Magnesium-antimony. — Antimony combines with mag- 
nesium forming the compound Mg,Sb,. The system has 


Zeit. anorg. Chem., 44, 117 (1905). 
2 Ibid., 46, 177 (1905). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 187 


been studied by Grube,! and the diagram constructed by him 
is shown in Fig. 97. A maximum occurs at 961° and 40 per 
cent. of antimony, corresponding to the compound Mg,Sb,. 
The eutectic horizontals are prolonged to the point indicating 
the concentration of the compound : there is, consequently, 














s do 

“ bey 

LMA» 
4ZGZ, 











eZ 



























































eh VIZ 
600° ee 4 ‘peas aa ‘ 
es 10 oat 40 50 6Q 70 ¥O 30 ISS 





Fi@. 97. 


no formation of mixed crystals. The compound crystallises 
in steel grey needles which are oxidised in the air. Alloys 
increase in brittleness up to 49-5 per cent. of antimony, and 
between this percentage and 95 per cent. of antimony are 
exceedingly brittle. 

Magneswum-bismuth.—Magnesium forms the compound 
Mg;Bi, with bismuth, as noted by Grube.? The diagram 


1 Zett. anorg. Chem., 49, 87 (1906). 
2 Jbid., 49, 183 (1906). 


188 CHEMICAL COMBINATION AMONG METALS. 


(Fig. 98) shows two branches intersecting in an eutectic 
point at about 18 per cent. of bismuth. The one branch has 
a maximum at 710° and about 40 per cent. of bismuth, which 
corresponds to the compound mentioned. The eutectic 
horizontal extends from pure magnesium to the composition 
of the compound, thus excluding the possibility of solid 
solutions being formed. The compound is very slightly 





























900° Bee 
800° = 
700° = 

QW | 

\ 
- MS SS a aN 
500 & N — 
KSN = alee 


NS . 


eS aa 


so? a 


oe 









































~44ZZ 








a oo On a kee who 0 On OF 400 


90 
own Ctlo me Ay 





Fie. 98. 


soluble in bismuth, and the eutectic alloy with bismuth 
consists almost entirely of bismuth. The compound is 
strongly exothermic. Freshly prepared it has a dark grey 
colour. It is very brittle ; in dry air it is stable, but in moist 
air it is oxidised in time to a black powder. 
Magnesium-nickel.—Nickel and magnesium form, accord- 
ing to Voss,t two compounds. Mg,Ni and MeNi,. The 
diagram (Fig. 99) shows that at the point D the compound 
MgNi, separates from the melt. On the liquidus curve, 


1 Zeit. anorg. Chem., 57, 61 (1908). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 189 


however, instead of a maximum, a flat portion is observed. 

Voss maintains that along this portion of the curve crystal- 

lisation takes place from two liquid strata. He has not 

succeeded in demonstrating this, as hot magnesium attacks 
D 





1§00° 


by, Ni, Mg 

1400° Zz 
1300° wi, i a 
Ve | 


° yA 
1200 y 


Us } 
1100° ZO a iz 
1000° hee Z Z 
Va 
a | 
Y 





Ni Mg 
































ISSSSS 
NS 






























































900° oe 
600° vA 44 
Pas 
700° ite. 
nS 
D 
600° SRS s . 
Ss SON 
500 SSS 
o sodas 
400° | — aie Vee Nae 50 COR MEOy S480) OS a 400 


: ean Oto Mog 
BIG; 99, 


porcelain strongly with resultant perforation and loss of 
liquid. At 768°, NiMg, separates. On the corresponding 
horizontal a maximal arrest is shown for 66 per cent. 
magnesium. 

The compound MeNi, crystallises in thin platelets. 
Freshly broken it has a red colour but alters quickly in the 


1909 CHEMICAL COMBINATION AMONG METALS. 


air. The compound Mg,Ni has not been prepared in a pure 
state ; alloys containing it are composed of the compound 
MgNi, surrounded by Mg,Ni, together with a certain 
quantity of the eutectic alloy. 


CALCIUM COMPOUNDS. 


Calcium-aluminium.—Donski,t working in ‘Tammann’s 
laboratory, has demonstrated the formation of the compound 





g00° 





CaAla 


50 | i 


A 

706 E ae < 

LE. IAS 

SL, NA 

fos ra a or <a 
bag Lob S 



































50 












































ae oO 10 20 ZO 40 50 60 40 80 30 4100 


5 Jpn Otome ‘OSs 
Fig. 100. 


CaAl,. The curve is shown in Fig. 100. Arrest points are 
noted at about 692° between 12 and 34 per cent. of calcium. 
Since two liquid strata are observed above 692°, it is supposed 
that they react, forming the compound CaAl, at the concen- 
tration, 25-5 per cent. of calcium, corresponding to the 
maximal arrest. Alloys up to 8 per cent. calcium have the 
colour of pure aluminium and are a little harder than this 
metal. They are fairly stable in air and cold water ; they 
react with hot water giving hydrogen. Alloys with a medium 
calcium content are brittle, porous and show exfoliations of 


1 Zeit. anorg. Chem., 57, 185 (1908). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 191 


coarse silvery-white crystals; they decompose cold water 
with evolution of hydrogen. 

The alloys richest in calcium are less brittle and are 
unstable in air. 

Calcium-thalium.—Thallium and calcium combine to form 
the compounds Cals, Ca,Tl,, and CaTl. These compounds 
have recently been examined thermally by Baar.t The pre- 
ceding researches of Donski? are somewhat incomplete. 





mt 
Ss 
) 


























‘M6 ii 
“TA 
2 
«<Q 





















































| 1 aaa ke 
‘ \ 
Tl; Ca SS ~ 4 s—| 600 
¥ Dhs< 
: — joe 
Lat tt Gehas 1 te 
us 
' ‘ 
an se : 
A NI T 400 
\ a 
AY LP S ae 
L aes 7 1 > Es) 
ke arr | = ‘y fe i 
af’ beeRS + 
ee 7 ~~ 1,9 200 
H 8 ! nN 1S 
iS | R 
baa ! | 
ts ! 
Aare Mi Bz BO ye; a FT | ye WT 
1 ‘ H AW pete | 
7 70 20 50 ¥O = 50 60 7 80. 90 700 
Qin fen, Ca 


Fia@. 101, 


Up to 8 per cent. of calcium (see Fig. 101) a small series of 
mixed crystals separates; then the compound CaT', is 
formed as is deduced from the prolongation of the eutectic 
horizontal at 310° up to the composition indicated by this 
formula. By addition of calcium the curve rises slowly to 
D, after which the compound Ca,TI, separates, its composi- 
tion being shown by a maximal arrest at 43-7 per cent. 
calcium and 556°. A maximum occurs at 969° and 50-5 per 
cent. of calcium, corresponding to the compound CaTl. The 


1 Zeit. anorg. Chem., 70, 366 (1911). 
2 Ibid., 57, 206 (1908). 


192 CHEMICAL COMBINATION AMONG METALS. 


remainder of the curve indicates two series of mixed crystals 
between the latter compound and pure calcium. 

All these alloys are unstable in air, in fact, so quickly do 
alloys with 55 to 85 per cent. calcium oxidise that micro- 





aa }CaSirg 


a 
‘NU 








600° 


ZL 





Dy, 


Se oe 


50 





500° 





50 








QML 


400° K 


















































SOS 
L 
ae ae 
Sn +| Ca Sn, 
150° 
ee: 10 20. 30 _ 40 
aa 7; tax CEG ae Ca 
BIG. 102; 


scopical examination is impossible. Alloys with 80 to 55 per 
cent. calcium are harder than thallium; those richest in 
calcium are very brittle. 

Calcvum-tin.—This system has been studied partially by 
Donski.' The formation of the compound CaSn, melting at 
624° has been noted. The curve (Fig. 102) rises directly 

1 Zeit. anorg. Chem., 57, 206 (1908). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 193 


from the melting point of tin to the melting point of the 
compound. A maximum occurs at 23-7 to 26-8 per cent. of 
calcium and 624°. Mixed crystals are formed between 25 
per cent. and 28-5 per cent. calcium containing high propor- 
tions of the compound. The alloys so far studied are 
oxydised in the air; those containing even as little as 2 per 
cent. of calctum decompose cold water with evolution of 
hydrogen. 

Calcium-lead.—Calcium forms with lead the compounds 








1200 
> 








fl O3 


: 








Wf) Mamma 
AY 
NS 
Vy) 








Add 





400 





Pb Ca,,+ Pb Ca 
6 





' ' 
nm ese o Pee es LA ins 


Joke | 

valet [a oT 

a a 7 a a lf 
id Se GOS at a i ‘ Ca 


1 
20 30 #0. 3o 60 7O a0 90 70 



































Pot" 











Fig. 103. 


CaPbs, CaPb, and Ca,Pb. The system has been studied by 
Donski! and Baar.? The curve (Fig. 103) is very similar to 
that for calcium-tin. At 25 per cent. and 649° there is a 
maximum due to the compound CaPb;. From the eutectic 
point D the curve rises quickly up to 982° and 51-8 per cent. 
calcium with separation of the compound PbCa. The 
curve then reaches a maximum at 1105° corresponding to 
the compound Ca,Pb. From 66-6 to 89 per cent. of calcium 


1 Zeit. anorg. Chem., 57, 208 (1908). 
3 Jbid., 70, 372 (1911). 
c.M. 1 es 


194 CHEMICAL COMBINATION AMONG METALS. 


mixed crystals separate. Maximum eutectic crystallisation 
occurs at 89 per cent. where the resulting alloy is a con- 
glomerate of calcium and saturated mixed crystals of 
calcium and the compound. These alloys are quickly 
oxydised in air to a black powder ; only those with 35 to 50 
per cent. of calcium have been examined microscopically. 

Calcium-antumony.—This system alse has been studied by 
Donski! up to a concentration of 9 per cent. of calcium. 
The existence of a compound seems probable, but it has not 
been possible to define it. The investigation had to be 
abandoned on account of experimental difficulties, namely, 
the high melting point of calctum and the extreme instability 
of the alloys in air. 

Calcium-bismuth. — Donski has also studied this system 
over a limited range. The formule of the compounds which 
probably occur are unknown. Arrest points have been 


observed between 20 and 37 per cent. of calcium at about 
500°. , 


CoMPOUNDS oF ZINC. 


Zinc-aluminium.—According to Tammann,? zinc forms 
with aluminium the compound Al,Zn,;. This compound is, 
however, not admitted by Heycock and Neville,? Shepherd,* 
and Eger,®> who have only encountered solid solutions in 
their investigations of the system. 

Zinc-antimony.—Antimony and zinc form the compounds 
Sb,Zn, and SbZn. The system has been investigated by 
Gosselin,® Monkmeyer,’ and Zemezuzny.® The curve con- 
structed by the latter is given in Fig. 104. There is a maxi- 
mum at 566° and 60 per cent. of zinc corresponding to the. 


1 Loc. cit. 

2 Lehrb. d. Metall., p. 222. 

FOS 1380 (1897): 

* J. Phys. Chem., 9, 504 (1905). 

5 Int. Z. f. Metall., 4, 35 (1913). 

6 Bull. Soc. d’ Encour., (5), 1, 1312 (1896). 
7 Zeit. anorg. Chem., 43, 182 (1905). 

8 Thid., 49, 384 (1906). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 195 


compound Sb,Zn;. Zemezuzny denies the existence of 
Znusb, believed by Gosselin to exist. In the region corre- 
sponding to this compound, he observed marked super- 
cooling due to the reaction Zn,Sb, + Sb =3ZnSb. The 
curve shows irregularities which, together with the formation 
of metastable crystals, are not observed if the liquid is seeded 
with crystals of ZnSb. This compound melts with decom- 
position, so that the curve only shows a transformation point. 


700° 





Zn, Sb, 


Zn|Sb 
50 L-: 





600" 





Wy 


930 


oo 
ie ee 


50 

















on 
A 
LM 
me 10 emg Ngee yo PCa ge 00 ABD 
dus ve can, CCG vere 


Hig. 104, 


PL 






































400° 
0 





Zn35b, shows a modification which was only observed on one 
side of the maximum. 

Zinc-manganese.—This system has been investigated by 
Parravano? up to 29-7 per cent. of manganese. He has 
noted the formation of the compounds MnZn, and MnZng. 
The diagram is shown in Fig. 105. The melting point of 
zinc 1s lowered a few degrees by the addition of manganese, 
so that the first eutectic is very close to pure zinc on the 
diagram and only 2° below it. ‘The two compounds are not 
indicated by well-defined arrests but rather by slackening in 


1 Gazz. Chim. Ital., 45, I., 1 (1915). 
. 13—2 


196 CHEMICAL COMBINATION AMONG METALS. 


the cooling curves, often accompanied by super-cooling. 
The alloys of this system are hard and brittle. 
Zinc-iron.—Iron forms with zinc the compounds Zn,Fe 
and Zn,Fe. ‘There are also three series of mixed crystals. 
The system has been studied by Wologdine,! Guertler,? von 
Vegesack ? and finally by Raydt and Tammann.‘ The 
diagram (Fig. 106) is that of von Vegesack, completed by 


In dn, 
fist 


a uN 


oO 











an 
a 
S 
~~ 























950} 
a 5 Fi) 5 20 25 TIT 
yin 95 90 85 go fe: 0° 
Fig, 105. 


Raydt and Tammann. At 777° and 25 per cent. of iron the 
melt separates the compound Zn,Fe which undergoes a 
transformation to the compound Zn,Fe at 662° and 15 per 
cent. iron. As above mentioned there are three species of 
mixed crystals, one up to-7 per cent. of iron, the second from 
7-8 to 11 per cent. of iron, and the third from 80 to 100 per 
cent. of iron. From 25 to 86 per cent., the alloys consist of 


1 Rev. d. Métall., 3, 701 (1906). 

2 Int. Z. f. Metall., 1., 355. 

3 Zeit. anorg. Chem., 52, 36 (1907). . 
4 Jbid., 83, 257 (1913). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 197 


saturated mixed crystals and the compound Zn,Fe ; from 
25 to 15 per cent., of the two compounds Zn,Ke and Zn;Fe 
and from 7:3 to -7 per cent., of the two saturated mixed 
crystals. 

Magnetic properties are observed in alloys from 26-2 to 
96 per cent. of iron; such properties diminish in intensity 
with decrease of iron content. The alloys with 11 to 22 per 


#50. 


W777 in 
emiecoene 
































bo nels oS | 
ce ee D> 
eee vee ee ae 
pie Aggy z 
i Che A ins ee oe 
X+Fe Zn, eles a ee Zan 
50 : g 











ESS 














So 



































4 00 





Fie. 106. 


cent. of iron containing the two compounds are exceptional. 
Probably their properties are due to the presence of small 
— quantities of iron. On heating, such alloys lose their 
magnetic properties. The iron-zine alloys are porous, hard, 
and very brittle. 

Zinc-cobalt.—This system has been studied by Levkonja * 


1 Zeit. anorg. Chem., 59, 319 (1908). 


198 CHEMICAL COMBINATION AMONG METALS. 


to a limited degree, and, up to the present, the only com- 
pound recognised is one having the formula CoZn,. The 
maximum corresponding to this compound occurs at about 
880° and 18-5 per cent. by weight of cobalt (see Fig. 107). 
From 5 to 13-4 per cent. of cobalt mixed crystals are formed. 





100) {OZ%, 
4 


oe 
| Zs 


300° 


1 LAA 
: a? 
| 

















300) 





50 Y ee. \ 
500 Zo ve co 
: SUES 
































001 
fk) 80 8§ 90 15 100 
——— > 2, ~~ Clitoris 21 





Fia. 107, 


From the melts of alloys containing 5 to 13-4 per cent. cobalt, 
there are separated, primarily, unsaturated mixed crystals 
which by addition of zinc pass, on cooling to 419°, to the 
saturated mixed crystals a. Levkonja has not observed 
magnetic properties in the alloys containing up to 18-4 per 
cent. of cobalt. 

Zinc-nickel. — Nickel forms with zinc the compound 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 199 


Zn,Ni and ZnNi, according to Tammann ! and Voss.2. The 
diagram constructed by the latter is given in Fig. 108. The 
melting point of zinc is not lowered by addition of nickel, 
and the curve rises directly from the zinc axis. Between 
14-5 and 23 per cent. of nickel a distinct interval occurs, 


Moor 
ae 
LY, 





1300° 





























ons 
200° Xé o Zz 
q eas 
100° “e MLD a 
VD 

100° ox lA Zeon 

:. a 
900" : G OS 2 

\ FS 


800" 











100° 





—_— 
+ gt cme ote 





ENN 
SS 


600" 





ee a ee ee 
I. 
pa el Baca ee ae 


900° 












































RIG, 108; 


together with a point of discontinuity. This range corre- 
sponds to the mixed crystals formed between Zn,Ni and Zn, 
the saturated mixed crystal occurring at 14:5 per cent. 
nickel. 

Microscopical examination confirms the results of thermal 
analysis. 


1 Métallurcic, 4, 781 (1907). 
2 Zeit. anorg. Chem., 57, 67 (1908). 


200 CHEMICAL COMBINATION AMONG METALS. 


CADMIUM COMPOUNDS. 

Cadmium-tin. — Information on this system is as yet 
incomplete ; the compound CdSn, is probably formed. The 
system has been investigated by Kapp?‘ and Stoffel,? and 
the diagram is shown in Fig. 109. Stoffel studied the alloys 
not only by thermal but. also by microscopical and dilato- 
metric methods; he also made determinations of electro- 
motive force. The last method, for some unknown reason, 
gave negative results, while the microscopical results were 
uncertain. He found a thermal arrest at 122° for all alloy 





50 


Cao Sn, 
300° XQ 
50 “< RS 


Bae 
Ba 0 Ee I SSSSESSISS 




































































LY 
Rg i ee 
e. 
100° | , 
ie ro cor 8 ae sm GO noe sO og ACO 
See a eC UO ree Cd 
Fig. 109. 


from 2-5 to 50 per cent. of cadmium and accompanying small 
changes of volume, of which, however, he was unable to note 
the maximum. : 
Cadmivum-antimony.—Antimony and cadmium form well- 
defined compounds, namely, CdSb and Cd,Sbg, the latter of 
which is in accordance with the known valencies of the two 
metals. The results obtained by Treitschke ® and Kurna- 
koff and Konstantinoff 4 are in fair agreement. The diagram 
(Fig. 110) shows a maximum at 455° and 50 per cent. An 


eutectic horizontal at 290° reaches to a point below the 


1 Ann. d. Phys., 6, 754 (1901). 

* Zeit. anorg. Chem., 53, 140 (1907). 
3 Tbid., 50, 217 (1906). 

4 [bid., 58, 12 (1908). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 201 


maxunum of the liquidus curve. Between 36 and 51-6 per 
cent. of antimony the compound CdSb separates as a solid 
phase of constant composition. By very slow cooling, 
another line (shown in dots on the diagram) is obtamed, which 
corresponds to Cd,5b., with a maximum at 423°. The 
cooling curves in this region show the formation of solid 
solutions. At 260 to 290° a reaction takes place in the solid 


EX | stabile 
i -xt.ye-- |metasrabile 
Yy 
500" Ly, 











Cd/Sb (cq Sv,) Gastabilg) 














00" 





30 

































































2 
CG 


(¢) 10 








Fia. 110. 


state with a rise of temperature of 20 to 30 degrees. This 
evolution of heat reaches a maximum for alloys containing 
50 per cent. of antimony. The transformation 1s, of course, 
that of Cd,Sb,, which is unstable, into CdSb, which is stable, 
and has a higher melting point (Cd,Sb, + Sb = 3CdSb). 
The transformation point corresponding to stable Cd,S8b, is 
at 409° and 66:5 per cent. of cadmium. 

Cadmium-chromium. — Hindrichs! in a study of this 

1 Zeit. anorg. Chem., 59, 427 (1908). 


202 CHEMICAL COMBINATION AMONG METALS. 


system did not succeed in obtaining positive results and our 
information 1s incomplete. 

Cadmium-iron.—The degree of chemical combination 
between cadmium and iron is not as yet completely known. 
The system has been investigated by Isaac and Tammann,! 
who found that on adding iron dust to molten cadmium and 
heating for a long time at 650° only one arrest point was 
obtained, which was in fact identical with the melting point 
of cadmium (321°). Microscopical analysis revealed the 
presence of conglomerates, which Isaac and Tammann 
believe to contain a compound of the two metals. It is 
doubtful whether any compcund rich in cadmium exists (as 
in the case of iron and zinc) or whether such compound is 
practically insoluble at its melting point. If such were the 
case a single arrest would be noted at the melting point of 
cadmium, which actually occurs. 

Cadmium-cobalt.—In this case aiso 1t 1s doubtful whether 
compounds are formed. The system has been studied by 
Levkonja,? who found an eutectic crystallisation in alloys 
with 2:5 to 10 per cent. cobalt at 316° to 6° below the melting 
point of pure cadmium. It was not possible to ascertain 
whether chemical combination took place. 

The alloys obtained did not exhibit magnetic properties at 
ordinary temperatures. 

Cadmium-nickel.—Nickel and cadmium combine to form 
the compound Cd,Ni. The system has been studied, though 
to a limited extent, by Voss,? whose observations do not 
extend below 15 per cent. on account of the volatility of 
cadmium. An eutectic horizontal at 821° extends from 
20 per cent. of nickel, the composition of the compound, to 
pure cadmium (see Fig. 111). Another horizontal is shown 
at 405° whose nature is not exactly understood. It evidently 
indicates a new species of mixed crystals. The nature of the 
solid phase above 502° is not known. 


1 Zeit. anorg. Chem., 55, 61 (1907). 
2 Tbid., 59, 322 (1908). 
3 [bid., 57, 69 (1908). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 208 


CoMpoUNDS OF Mercury (AMALGAMS). 


The amalgams are of considerable historical importance 
in the study of the solubility of metals. It may be men- 
tioned that Ramsay and Tammann used mercury as a solvent 
in their studies on the atomicity of metallic molecules by the 
cryoscopic method. Our knowledge of the chemical com- 
pounds of mercury with other metals, although abundant, 1s 
somewhat inexact, as only in a few instances has the thermal 
method been used to ascertain formule. We shall, how- 


700° 





NiCd 


600° 


Ge 


ice ara oh ri 
| Zaz 
| ies 














3007 





























7a as: 30 os 90 97 4100 
: 2. 3 a © & fire Cc 
Bra. 1, 


ever, not confine our description to the amalgams studied 
by the thermal methods which have so much enlarged the 
field of scientific investigation. A reliable summary of our 
knowledge of the various amalgams studied by the older 
methods of chemistry has been made by Ley.! We shall 
now allude briefly to the information which we actually 
possess of the crystalline amalgams. 
Mercury-aluminwm. — The aluminium amalgams have 
received considerable attention, but at present little is known 


of the capacity for chemical combination between the two 
metals. 


1 Cf. Handbuch d. anorg. Chem., R. Abegg, Vol. IL., pp. 569 et seq. 


204 CHEMICAL COMBINATION AMONG METALS. 


Cossa t prepared an amalgam by fusion in an atmosphere 
of inert gas; Tarugi? allowed mercury vapour to act on 
aluminium. 

The compound Heg,Al, is supposed to exist, but this is not 
certain. Aluminium amalgam is chemically very reactive.® 

Mercury-galium.—tThis system has not yet received any 
attention. Ramsay 4 states that gallium dissolves easily in 
mercury, in which it agrees with thallium. It is, therefore, 
not improbable that the two metals combine chemically. 

Mercury-indium.—T. W. Richards and Wilson ® studied 
the electro-chemical potential of indium amalgams, and 
obtained values in excess of those calculated by the mixture 
rule. According to Hildebrand ° the compound Hg,In can 
probably occur. 

Mercury-thallium.—- This system has been studied by 
Kurnakoff and Pushin,; who noted the existence of the 
compound Hg,T'l. Studies have also been made _ by 
Regnault * and Carstanjen,* the former of whom affirmed the 
existence of the compounds Hg,Tl, and Hg,Tl,. The most 
recent investigations are those of Paulovitch,’® who has con- 
firmed the work of Kurnakoff and Pushin and added some 
considerations on irrational dystectics. 

The behaviour of thallium with mercury resembles to an 
extent that of the alkali metals which give the type RHgp. 
The diagram of Kurnakoff and Pushin (Fig. 112) gives a 
maximum at 15° and 33:3 per cent. of thallium. The branch 

1 Nuovo Cimento, (2), 8, 75 (1870). 

2 Gazz. Chim. Ital., 34, IL., 486 (1904). 

3 Of. Tissier, C. R., 49, 54.(1859); Casamajor, Chem, News, 34, 34 (1876); Jehn, 
Ber., 11, 360 (1878) ; Kronchkoll, J. de Phys., (2), 8, 139 (1884) ; Ramsay, J. C. S., 55, 
521 (1889) ; Schumann, Wied. Ann., 48, 101 (1891); Coehn and Ormandy, Ber., 28, 
1505 (1895); Biernacki, Wied. Ann., 59, 664 (1896); Humphreys, J. C. S., 69, 1679 
(1896) ; Konovaloff, Chem. Centr., 1896, II., p. 338; Richards, Chem. News, 74, 30 
(1896). 

1 J.C. S., 55, 553 (1889). 

5 Zeit. phys. Chem., 72, 141, 157, 164 (1910). 

6 J. Amer. C. S., 35, 513 (1913). 

7 Zeit. anorg. Chem., 30, 104 (1902), 

8 (C, R., 64, 111 (1867). 


9 J. prakt. Chem., 102, 84 (1867). 
10 Journ. Russ. phys.-chem. Soc., 47, 29—46 (1915) ; Bull. Soc. Chim., (4), 20, 2 (1916). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 205 


of the curve on which this maximum occurs belongs therefore 
to the compound TlHg, which melts without decomposition. 
Along the branch «, liquid amalgams separate. At low tem- 
peratures thallium is very soluble in mercury and lowers the 
freezing point of the latter to — 60°, which isthe temperature 





300° 





90 


ye 





200° 





90 





100° 





90 


2 
-50° c Be Of 


LL LD bp TF oe 


> 





= 
RAs 
EOSIN 



























































e) 10 10 4O 4o $0 6O %0 


80 90 400 
> Yin Cori Hg 





dices Oe 


of eutectic solidification. It may be added that this is the 
lowest freezing point hitherto observed for any alloy. 
Mercury-tin.—Tin dissolves in mercury, even at ordinary 
temperatures, with evolution of heat. According to Rooze- 
boom ! and Van Heteren,? tin and mercury form solid solu- 
tions. Pushin? has also noticed the formation of solid 


1 Verh. K. Ak. Wetensch., Amsterdam, 420 (1902). 
2 Zeit. anorg. Chem., 42, 129 (1904). 
3 Tbid., 36, 207 (1903). 


206 CHEMICAL COMBINATION AMONG METALS. 


solutions. Kupffer! and Matthiessen * have determined the 
specific gravity of these amalgams. 'Tammann ® studied the 
effect of the addition of small quantities of tin on the freezing 
point of mercury. He found that the freezing point was 
raised as follows :— 


063 gram. Sn dissolvei in 100 gm. Hg raised the f.p. -06° 


148 oe) ” re) ” 1h fg 
° 

apd 9 oe) ” ” 2-1 

281 oe) oe) ” oy) 24~ 


According to Tammann the existence of the compound 
Hg.Sn is probable, but the actual data render more probable 
the existence simply of isomorphous mixtures of the two 
metals. 

Mercury-cervum.—the solubility of cerium in mercury was 
observed by Winkler,* and by Muthmann and Beck.® 
Cerium is very soluble in boiling mercury. Nothing is 
known of the capacity for combination of these metals. 

Mercury-antumony.—Mercury is without action on anti- 
mony in the cold ; an amalgam is formed at higher tempera- 
tures. Amalgams of mercury have been prepared by means 
of the usual indirect methods by Béttger ® and Vortmann.? 
According to Partheil and Mannheim,’ the compound 
Hg.Sb, 1s probably formed. 

Mercury-uranvum.—The amalgams of uranium, prepared 
electrolytically by Férée,? lose mercury on heating to 242°, 
leaving a residue of uranium which ignites spontaneously. 

Mercury-chronium. — Chromium amalgams have been 
prepared by the direct fusion of the two elements. Schén- 
bein ?° and Vincent ™ obtained them by acting upon sodium 


1 Ann. Chem., 40, 293. 

2 Pogg. Ann., 112, 445. 

3 Zeit. phys. Chem., 8, 441 (1889). 
4 Ber., 24, 1883 (1891). 

5 Ann. Chem., 331, 56 (1904). 

6 J. prakt. Chem., 12, 350 (1837). 
+ Ber., 24, 2762 (1891). 

8 Arch. Pharm., 238, 160 (1900). 

® Bull. Soc. Chim., (3), 25, 622 (1901). 
10 Jahresber., 1861, p. 95. 
4 Phil. Maq., (4), 24, 328 (1862). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 207 


and potassium amalgams with concentrated chromium 
chloride solution. They have also been prepared and studied 
by Moissan. ? | 

Myers ? and Féree* obtained chromium amalgams by 
electrolysis of chromium sulphate solution with a mercury 
cathode. 

The compounds He,Cr and HgCr have been described in 
chemical literature. The compound Hg,Cr loses mercury 
easily under pressure giving the other hypothetical com- 
pound HgCr. This in its turn loses mercury on heating 
to 300°, leaving a residue of chromium (I érée). 

It is probable that these metals form solid solutions rather 
than definite compounds. 

Mercury-molybdenum. — The amalgams of molybdenum 
have been prepared by electrolysis of a solution of molybdic 
anhydride in hydrochloric* or sulphuric’ acid. Férée ° 
obtained a semi-solid amalgam by electrolysis: from the 
crystalline phase, the compounds Hg Mo, Hg,Mo, and 
Hg,Mo, separated under pressure. ‘These compounds, 
however, lose their mercury completely on heating, leaving 
behind a residue of pyrophoric molybdenum. 

Mercury-manganese. — Manganese amalgams have been 
prepared by Bottger,’ Giles,® Moissan,? and J. Schumann,!°® 
by the action of sodium amalgam on manganous chloride. 
Ramsay “ obtained an amalgam by electrolysis of manganese 
chloride solution using a mercury cathode. ‘The researches 
of O. Prelinger !* must also be mentioned; from these the 
existence of the compound Mn,Hg,; is argued. 


C. R., 88, 180 (1879); Ann. Chim. Phys., (5), 21, 250 (1880). 
2 J. Am. C. S., 26, 1126 (1904). 
8 CO. R., 121, 823 (1895). 
4 Zeit. Klektroch., 12, 146, 154 (1906). 
5 J. Am. C. 8., 26, 1124 (1904). 
6 C. R., 122, 733 (1896). 
7 J. prakt. Chem., 12, 350 (1837). 
8 Phil. Mag., (4), 24, 328 (1862). 
® C. R., 86, 180 (1879). 
10 Wied. Ann., 43, 110 (1891). 
1 J.C. S., 55, 532 (1889). 
12 Ber. Wien. Akad., 102, 346 (1893). 


208 CHEMICAL COMBINATION AMONG METALS. 


Mercury-iron.—These amalgams have been prepared 
exclusively by indirect methods, either electrolytically, or 
else by the action of alkali amalgams on solutions of iron 
salts. Cailletet 1 showed that iron may be superficially 
amalgamated. From amalgams containing about 15 per 
cent. of iron Joule? obtained, by the application of pressure, 
a crystalline phase of composition FeHg. Zamboni * pre- 
pared an iron amalgam by electrolysis of ferrous ammonium 
sulphate, usmg a mercury cathode, Rammann,* by the 
same method as Joule obtained a solid phase of composition 
Fe,Hg5. It is not, however, certain whether mercury and 
iron combine chemically. 

Mercury-cobalt and ‘mercury-nickel. — These amalgams 
have been little studied with reference to the capacity of 
their components for chemical combination. They have 
been prepared by Darmour,? Moissan © and Schumann.’ 

Mercury-platinum, ete.—Little is known of the amalgams 
of platinum, palladium, osmium, iridium, rhodium and 
ruthenium. Joule ® obtained a crystalline amalgam of 
‘platinum of composition PtHg,,. It is most probable that 
these metals form simple isomorphous mixtures with 


mercury. 


| Compounds of Metals of Group ITI. with Metals of 
other Groups. 


COMPOUNDS OF ALUMINIUM. 


Aluminium-cervum.—The system has been investigated by 
Vogel,® who claims that five compounds are formed, namely, 
AlCes, AlCe,, AlCe, Al,Ce, and Al,Ce. ‘T'wo of these com- 


sc OP «ie es 1250 (1857). 
2 J.C. 8., (2), 1, 378 (1863). 
3 Nuovo nae (4), 2, 26 (1895). 
4 Ber., 14, 1433 (1881). 
Ce prakt. Chem., 17, 346 (1839). 
8 OC. R., 88, 180 (1870). 
7 Wied. Ann., 48, 111 (1891). 
8 Jahresber., 1850, p. 333; 1863, p. 280. 
9 Zeit. anorg. Chem., 75, 41 (1912). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 209 


pounds, Al,Ce and Al,Ce, have melting points much above 
those of their components. The curve (Fig. 118) shows two 
maxima, One very pronounced at about 1460° and 88 per 
cent. of cer1um due to the compound CeAl,,and the other, not 
£0 pronounced, at about 614°, corresponding to Ce,Al. The 
asymmetry of the latter maximum is due in all probability to 
the compound CesAl being strongly disseciated, while the 





4500p 











































































































CeAly 
GeAcaA Gul ers! (CAL 
4£00 Loa 
re | ee 
age ee 
Y 4 . 
oe : exe ais Seat 
4200 Stee z 
pean Z 
eer | 
4100 = ere 
Fe Ze 
| 
4000 — —— 
Pe | 
—— : 
90 Se an ois 
ae se 
| ee eae ZA 
Q00P a ee, Wag 
YZ Sie “A 
/7 Ss af 
ae! See i 
= NI 
600 YY, — Sas IF 
ae Be tS are? oma Sd 
Sa0% lo 10 sia 40 20>" 3 GO 70 go 90.) 6.406 
: peti NEN, PIES SSS wal 
Fia. 113. 


compound Ce,Al is less disscciated. The latter compound, 
formed at 33 per cent. of aluminium, melts at 595° with 
decomposition into CeAl and a melt; CeAl separates primarily 
in beautiful prisms which at 780° split up into CeAl, and a 
fused mixture. Above 700°, between 35 and 50 per cent. of 
aluminium, weak thermal effects are noted which may be due 
to the occurrence of lanthanium and didymium in the cerium 
used for experiment. After CeAl,, which separates at about 


67 per cent. of aluminium, comes the compound Al,Ce which 
C.M. 14 


910 CHEMICAL COMBINATION AMONG METALS. 


separates at 1245° and 80 per cent. of aluminium. ‘This 
compound undergoes a polymorphic transformation at 1005° 
which is shown in the diagram as a weak thermal effect. 
The change from the form £, stable at higher temperatures, 
to the form «, stable at lower temperatures, is characterised 
by a contraction. 

The cerium-aluminium alloys are in general stable in the 
air, unacted upon by water, and more resistant to the action 
of acids than the pure metals. They exhibit distinct hard- 
ness between 35 and 80 per cent. of aluminium with a maxi- 
mum for CeAl,. With this hardness is associated extreme 
brittleness. 

Alumimium-antumony.—The various chemical combina- 
tions of these metals, if indeed they exist, have not been 
well elucidated up to the present. The existence of a com- 
pound AlSb seems certain. Wright! noted that antimony 
and aluminium form an alloy with a high melting point, and 
containing 81-6 per cent. by weight of antimony (correspond- 
ing to AlSb). Roche? and Gautier? have confirmed this 
result. The study of the equilibrium system is due to 
Campbell and Matthews * and, later, to Tammann.® 

The fusion diagram (Fig. 114) shows two maxima, one at 
50 to 53 per cent. of aluminium and the other at 90 per cent. 
aluminium. Of these, the former corresponds to the com- 
pound AlSb ; no crystalline species has been found to corre- 
spond to the latter maximum. ‘Tammann has attempted to 
solve this problem by showing that the form of the curve is 
different when this smgle compound of aluminium and anti- 
mony is formed slowly from its fused components. If the 
compound is formed more quickly there may occur a dis- 
placement of the maximum, an increase of the quantity of 
one of the components, or even the appearance of a second 


J. C.8. I., 1892, p. 493. 

Mon. Scient., (4), 7, 269 (1893). 
Bull. Soc. d Encour., (5), 1, (1896). 
4 J. Am. C. S., 241, 259 (1902). 

5 Zeit. anorg. Chem., 48, 53 (1906). 


1 
2 
3 


HOMOPOLAR INTERMETALLIC ‘COMPOUNDS. 211 


maximum. The compound AlSb is formed slowly from its 
components at about 700°; at 1100° the reaction proceeds 
very rapidly. (Cf. p. 7). 

Aluminium-manganese.—T wo compounds of these metals 
with each other occur, but their composition has not been 
ascertained with certainty up to the present. According to 
Gwyer,! their formule are probably AlMn, and Al,Mn, 
respectively. Guillet? prepared alloys of alumimium and 


1100° 





Fo Pat 








VA 
Dy 
or 























AY 


NN NNN 
NWMAAYT 


NNN 
ASS 

















\\ 
WN 
IN 
aS 

N 

Ni 

\ 



































Fr@,. 114, 


manganese and found the compounds Al;Mn, Al,Mn, and 
Al, Mn. | 

Hindrichs * has studied the system by means of thermal 
methods ‘The diagram (Fig. 115) shows that the melting 
point of manganese is raised by addition of aluminium. At 
about 90 per cent. of manganese there occurs, at 1279°, the 
first separation. Between 10 and 35 per cent. of aluminium 
the temperature only changes by about 2°. Further, on the 
cooling curves of melts from 5 to 40 per cent. of aluminium, 


1 Zeit. anorg. Chem., 57, 150 (1908). 
2 O. R., 134, 236 (1908) ; Le Génie Civil, 41, 139, 156, 169, 188, 363, 377, 393 (1902). 
3 Zeit. anorg. Chem., 59, 44 (1908). 

14—2 


212 CHEMICAL COMBINATION AMONG METALS. 


distinct crystallisation intervals occur with a minimum at 
14 per cent. of aluminium. The temperature change of 2° 
on the fusion curve may well be due to ordinary experimental 
error, for the temperature along that portion of the curve 
should either remain constant or else show a maximum. In 





1500° 














Al M ng 
1400 | 
; Al, Mn 
1300 \ ; <7 
ASF ERL | 
1200 4 SS as OP 
Wy 
100° POLE feclee| 




















WG y { ; 
: ; ee p> 
se oe IAS, ne 















































600 D 





Fie. Lib, 


the former case a compound would be formed from the melts 
in question, in the latter case there would occur a crystallisa- 
tion of a series of homogeneous melts into a continuous series 
of mixed crystals, of which that mixed crystal with the 
highest melting point would be a definite compound. 
Thermal analysis does not enable us to decide which 1s 
actually the case that occurs. At 1040° to 1050° small arrests 
are noted in the alloys up to 45 per cent. of aluminium with a 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 2138 


maximal arrest at about 27 per cent. which should be due to 
the decomposition of mixed crystals with 50 per cent. of 
aluminium into manganese and the crystals «. If the mixed 
crystals formed from the melt consist of the compound 
AIMn, there ought here to be a decomposition of AlMn, into 
manganese and the mixed crystals «. From 35 to 73 per 
cent. mixed crystals separate. Between 73 and 95 per cent. 
there exists a gap in miscibility. The formation of mixed 
crystals is accompanied by super-cooling. At 670° the melt 
« reacts with the saturated mixed crystals forming a com- 
pound which may be detected by microscopical examination. 
Its formula is probably Al,Mn. 

Aluminium-iron.—Gwyer ! states that these metals form a 
compound Al,Fe. Between 100 and 43 per cent. of iron (see 
Fig. 116) a series of mixed crystals is formed. From 380 to 
50 per cent. of iron there occur on the cooling curve either 
breaks due to primary separation or else eutectic arrest 
points ; these occur at 1087° for alloys with 65, 62:5 and 60 
per cent. of aluminium, and at higher temperatures for 
alloys between 57-5 and 50 per cent. of aluminium. From 
67-5 to 76-8 per cent. aluminium, crystallisation intervals are 
noted which correspond to a series of mixed crystals of which 
the last member, at about 75 per cent., probably represents 
the compound FeAl,. In the alloys from 41 to 0 per cent. of 
iron the proportion of FeAl, diminishes, while that of 
aluminium increases. In the cooling of these alloys a very 
small thermal effect 1s observed at 550°, believed by Gwyer 
to be due to the formation of a compound from Al,Fe and Al ; 
this compound is, however, not detected by Poni 
analysis. 

The reaction between the two metals is accompanied by 
such an evolution of heat that Gwyer was unable to make 
use of porcelain fusion tubes and was obliged to substitute 
tubes of magnesia. 

Alumimum-cobalt.—These metals combine, forming the 


1 Zeit. anorg. Chem., 57, 129 (1908). 


214 CHEMICAL COMBINATION AMONG METALS. 


compounds Co;Al,3, Co,Al, and CoAl. This system also was 
studied by Gwyer.t The curve (Fig. 117) is somewhat 
similar to that for FeAl. It shows two discontinuities and a 
maximum. Between 100 and 80 per cent. cobalt mixed 
crystals of the two metals are formed. From 80 to 50 per 


1500° Pa 


400° 


D>. Fe Al, 
1200 LD 


100° a 

















KS 
\N 
»S 


Ik 





1000 


RUS 


MESES 





—_ 


SS 
N 
Ss 











WING 

NEN 
NSS 5S 

Sse 












































ho 10 10 90s, 00) SOV OO RO 20s. 0: 7400 
= Me jaw CUlo nrg pAWh 





FIG: F116, - 


cent. all cooling curves show crystallisation intervals, but 
microscopical analysis shows that only those alloys with 
50 to 65 per cent. cobalt have a homogeneous structure, 
while from 80 to 65 per cent. two structural elements are 
observed. Since these alloys even on long annealing do not 
acquire homogeneity, Gwyer concludes that there is here an 


1 Zeit. anorg. Chem., 57, 136 (1908). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 215 


interrupted series of mixed crystals (with a maximum) or 
else a gap in miscibility between two phases. At 1628° and 
50 per cent. the compound CoAl crystallises. The latter, 
reacting with the melt, gives at 1165° and 22:5 per cent. of 





1700° ‘; Goat 
com Ta 


(0) 4a eee weer ee 





1500", 





A) 


WY 





1400° 


Kee | ARS ye ema 
1300° YE 
ye bes 
1200 GY 
N00" | ee i) 
iG 
1000" | Z | 
900 | | f : ip 


aE 
23 fi 































































































a 
A00" 3 
0 10 20 %0 40 50 BO he ON) OO 
a —>7,in Qtowe AL 
BIG. hy, 


cobalt, the compound Co,Al;. At 1110° small breaks are 
noted which probably indicate a polymorphic transforma- 
tion. From Co,Al; and the melt, crystals of Co,Al,s 
separate at 940° and 18 per cent. cobalt. The formule of 
the last two compounds are indicated by the positions of the 
- maximal/arrests, | 


916 CHEMICAL COMBINATION AMONG METALS. 


Gwyer observed very small thermal effects also at 550° ; 
he believes it possible that there are two such effects, one for a 
reaction between *Co3Al,, and aluminium, and the other in 


alloys richer in Co;Al,, due to a polymorphic transformation 
in this compound. 


1700°r 





1600° 























































































































10 10 30 Lo 50 GO 290° 4 


aeehO O 
ee ONS CICA Coir Al 


Fig. V18: 


Aluminium-nickel.—These metals form the following com- 
pounds: NiAl,, NiAl, and NiAl. The system was studied 
by Gwyer (loc. cit.). The curve (Fig. 118) shows a maximum, 
two discontinuities and an eutectic poimt. Between 100 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 217 


and 73:15 per cent. of nickel there separates a series of 
mixed crystals of the two metals. From 638 to 73:5 per cent. 
small arrests are noted at 1370°; these alloys consist of two 
species of crystals. At lower temperatures, however, this 
lack of miscibility changes; in fact the alloy with 63 per 
cent. of nickel after long annealing has a homogeneous 
structure. From 78 to 50 per cent. of nickel there is a series 
of mixed crystals of NiAl and nickel. The maximum shows 
that at about 1640° and 50 per cent., the compound NiAl is 
formed. At 1180°, by action of the melt containing 25 per 
cent. nickel on the crystals of NiAl, the compound NiAl, is 
formed at a concentration of 34 per cent. These crystals of 
primary separation react at 825° with a melt contaming 
15 per cent. nickel, forming at 25 per cent. a compound which 
is probably NiAl,. 

Aluminium-chromium.—The compound AlCr, 1s probably 
formed from these two metals. The system was studied by 
Hindrichs ! to a limited extent. Working with alloys con- 
taining more than 70 per cent. of aluminium, the temperature 
of fusion was so high that the aluminium attacked and 
destroyed the magnesia tubes which were used. It was, 
therefore, necessary to study these alloys by micrographical 
methods alone. At 644° (see Fig. 119) arrests were noted as 
far as 60 per cent. of chromium. By extrapolation it would 
appear that they die out at 85 per cent. chromium. From 5 
to 70 per cent. there are also arrests at 975°. The separation 
which occurs here is often accompanied by slight super- 
cooling. On the higher branch of the curve there probably 
occurs the separation of compound with a very high melting 
point. Microscopical examination shows that alloys from 
85 to 96 per cent. of aluminium have a homogeneous 
structure ; they represent mixed crystals of chromium and a 
compound of the two metals. The formula is probably 
AlCrg, which would require 85-12 per cent. by weight of 
chromium. 

1 Zeit. anorg. Chem., 59, 433 (1908). 


218 CHEMICAL COMBINATION AMONG METALS. 


THALLIUM COMPOUNDS. 


Thallium-lead.—With thallium, lead probably forms the 
compound PbTl’. The system has been studied by Lev- 
konja ‘ and by Kurnakoff and Pushin.” It is of interest by 
reason of certain considerations which may be made with 


1500° 





4400 





1300 





nZZ 
BINNS 
R&S QQ 


its ac et 
606 —— 










































































60 0 00 
0 40 “i ey belts ae Av : 
PEG UES? 


reference to the application of thermal analysis to the 
interpretation of equilibrium diagrams. Hach metal raises 
the melting point of the other, and the fusion curve passes 
through a point representing a much higher temperature 
than either of the melting points of the pure metals. 


1 Zeit. anorg. Chem., 52, 454 (1907). 
2 Ibid., p. 435. L. "Rolla studied the thermo-electric power and specific volume of 
these alloys. Gazz. Chim. Ital., 45, I., 185 (1915). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 219 


Levkonja holds that this maximum (see Fig. 120) which 
occurs at about 275° and 34 per cent. of lead indicates the 
compound PbTIl, which forms solid solutions with both 
components. Jurnakoff and Pushin, however, contend 
that the curve merely indicates the formation of solid solu- 
tions and belongs to Roozeboom’s second type (see p. 16). 
This question can only be resolved by microscopical exami- 
nation. Kurnakoff has, however, given powerful support to 
his contention by observing that the addition of tin displaces 


380° | << 


360"! SS 


———— A Dy 
Pita Wi 


























NN 
NS 


300° 












































Sy 
bes eee ee | 


280 
(¢) 





10 90 30 Lo 50 6O- 10 80 a6 ADO 
Peseta ete OE ©) 8 Sy Oe wed 
Fia. 120. 


the maximum to a point where Tl: Pb = 1 : 2:5 instead of 
1-7 —1-8: 1. 

Thallum-antimony.—Antimony and thallium combine to 
form the compound SbTl,.. The system has been investi- 
gated by Williams? (see Fig. 121). Pure antimony crystal- 
lises from melts rich in that metal. Thallium occurs in two 
polymorphic forms which transform at 225°. From melts 
between 29-8 and 22 per cent. of antimony, pure thallium 
does not separate, but a series of mixed crystals. At 195° 
conglomerates are formed which consist of antimony and 
mixed crystals of « Tl with 22 per cent. of antimony ; from 
22 to 0 per cent. they consist of a series of mixed crystals of 


1 Zeit. anorg. Chem., 50, 129 (1906). 


220 CHEMICAL COMBINATION AMONG METALS. 


composition corresponding to that of the melt. At 187° or 
8° below the eutectic temperature and 25 per cent. of anti- 
mony a new species cf crystals is formed, namely, the com- 
pound SbTl;, with a super-cooling of about 2°. 

Alloys with less than 50 per cent. of thallium are hard, 
brittle and capable of receiving a polish. With increase of — 
thallium they become softer and can only be polished with 
difficulty. 

Microscopical analysis has confirmed these results, 


JOO === ) oN | ae 
600 ; Bee eee 


: SFE a“ AN \ 
: EIN 
400 meee ae = < \\ A NN NW 




























































































fo) 10 20 Jo LO 50 690 70 go go 100 
ate ect ye oes 
~ 


Fie. 121. 


although at 187° Williams failed to obtain a homogeneous 
alloy, for there occurred an admixture of rod-like crystals of 
antimony. On subjecting this heterogeneous alloy to pro- 
longed annealing, however, the free antimony diminished in 
amount and finally almost disappeared. At 22 per cent. the 
quantity of the compound decreased while that of the mixed 
crystals « TISb increased. 
Thalliium-bismuth.—This system is of particular interest. 
The two metals combine but, as was mentioned in a preceding 
chapter, their combination cannot be reconciled with the law 
of definite proportions. Chikashigé ! first studied the system 


1 Zeit. anorg. Chem., 51, 330 (1906). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 221 


which was subsequently examined by Kurnakoff, Zemezuzny 
and Tararin.t. The fusicn diagram shows three maxima, two 
of which are distinct and one less pronounced. The first 
of these maxima occurs at -9 per cent. of bismuth at 301-5° ; 
it corresponds to the separation of a solid solution of bismuth 
in thallium (phase 8). At 5:8 per cent. these solid solutions 


20: 





BilTl, 
300° o> 











90 


R 


wy 
a J Ds 
“LD \ eS 


CLG LE CLI S SSS 4 
, Li INS 
: a 
Bx 














} 





/ 
s 

































































aes ie tae rel | 
HH 
50 a> | 
¢| f 
+ 
Sli 
20 ae | 
Q 10 20 30 40 50 GO tO. BO 90.400 
ae ee AY 4 ur Aftorme GL, i 
BIG 122. 


cease to exist. The second maximum is at 12-05 per cent. of 
bismuth and 803-7° ; between 5:9 and 33 per cent. of bismuth 
more solid solutions are formed. The third maximum is at 
62-8 per cent. and 211-7°, and a further series of solid solu- 
tions e crystallises from 55 to 64 per cent. of bismuth. The 
last branch of the curve corresponds to the separation of 
pure bismuth without any notable formation of solid 
solutions. 
1 Zeit. anorg. Chem., 83, 200 (1913). 


222 CHEMICAL COMBINATION AMONG METALS. 


According to Kurnakoff and his co-workers, the three 
maxima do nct correspond to any rational atomic propor- 
tions. Chikashigé, though admitting the irrationality of 
two of the maxima, maintains that the third corresponds to 
the formula Bi,Tl,. | 

Kurnakoff and his collaborators from a study of the 
electrical conductivity, compressibility, hardness and micro- 
scopic structure of these alloys conclude that no definite 


formula can be assigned to correspond with any of the three 
maxima. 

































































2000° 
1800°¢ 
ie a 
cE ae a 
1600 Va, 
1400 Ze Pri Ti 
y s “ 
1200 eg es és 
MLA 
WALZ 
"800° A. Ar As os 
IZZZEZe = 
: Wg LY > 
400% G Zan it 
| Pr +Prm VIMLLME LID Pye wo 
200 ' 
| Pt Tl 5 Tl 
0" ! 





DO: 40" 90° (S00 20 150, 60.10) 80 OO 100 


eee ae mw CCCor we 


BiG, 125: 


Thallvum-vron.—Nothing is known of the alloys of.these 
metals. Isaac and Tammann,! who made some preliminary 
investigations, obtained no results, the boiling point of 
thallium being lower than the melting point of iron. They 
did in fact observe a certain lowering of the melting point 
of iron by thallium, but the thallium very quickly distilled 
off unaltered. 

Thallium-platinum.—According to Hackspill,? thallium 


1 Zeit. anorg. Chem., 55, 61 (1907). 
2 C. R., 146, 820 (1908). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 223 


and platinum form a compound TIPt. Thallium dissolves 
easily in platinum. The curve (Fig. 123) shows that the 
addition of platinum to thallium causes lowering of the melt- 
ing point by a few degrees. With increase of the content in 
platinum there occurs, at 50 per cent. and 685°, the sepa- 
ration of crystals of the formula PtTl. The curve then falls 
slightly and subsequently rises so that at 70 per cent. of 
platinum it reaches about 1000°. Platinum forms solid 
solutions with thallium. Between the compound and 
platinum no solid solutions are formed according to Hack- 
spill’s observations. 


Compounds of Metals of Group IV. with Metals of 
other Groups. 


COMPOUNDS oF TIN. 


Antimony-tin. — It is probable, though not certain, that 
these metals combine to form a compound SbSn. The 
system has been studied by Reinders,’ Gallacher? and 
Wilhams.? The diagram constructed by the last named is 
shown in Fig. 124. On cooling melts rich in antimony, a 
series of mixed crystals of the two metals separates. At 420°, | 
from 50 to 90 per cent. of antimony there forms, after separa- 
tion of mixed crystals, a new crystalline species surrounding 
the mixed crystals rich in antimony. There are no corre- 
sponding arrests on the cooling curve but only slackening. 
At 243°, however, up to 50 per cent. of antimony, distinct 
arrests are noted. The mixed crystals in all probability are 
transformed into SnSb crystals at 50 per cent. by addition of 
tin. The existence of this compound is, however, not 
well established. 

Tin-bismuth. — Chemical combination between these 
metals, although stated to take place by Tammann,* is 


1 Zeit. anorg. Chem., 25, 113 (1900). 

2 J. Phys. Chem., 10, 93 (1906). 

3 Zeit. anorg. Chem., 55, 14 (1907). : 
* Lehrb. d. Metall., p. 222 (1914), Leipzig. 


294 CHEMICAL COMBINATION AMONG METALS. 


excluded by the complete investigations of Mazzotto.! ‘This 
is also shown by the experimental work recorded on p. 45. 

The system has also been studied by Stoffel? and 
Lepkovsky.? 


650° 


600°444, 
ZY 
50| Zz 








4 


NS 





‘ 
ye 








LLMLL 





MM» | 
LL. YA 




















A00° 12 P 
(GLUON 
300° WAZ eps 
; QU 





















































LEP A VEE ES CILIA 
| Si 
orcs koran 
me 10 30 G % g fe) 
10 40 ROK Ye) (2) (@) O 10 
——> 7, Cihoun on . 
BIG. vat, 


T'vn-manganese.—Manganese forms with tin the com- 
pound SnMn,, SnMn, and possibly SnMn. The diagram 
(Fig. 125) has been traced by Wiliams. The three com- 
pounds are represented by three breaks in the curve, the 
first at 988° and 80-1 per cent. of magnanese, the second at 

1 Mem. Inst. Lomb., 16, (1886), and Nuovo Cimento, 18 (1900). 
2 Zeit. anorg. Chem., 58, 148 (1907). 


3 Ibid., 59, 287 (1908). 
4 Ibid., 55, 26 (1907). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 295 


898° and 64-8 per cent. of manganese, and the third at 541° 
and 15 per cent. of manganese. The reaction which gives 
rise to the latter does not, however, take place to completion, 
but part of the crystals of SnMn, surrounded by SnMn are 
deposited in the presence of the melt. 





Mr 4 Sn Mr,Sn 















Mh Sn 





Y 
Yn, Sir 





















































Sn | 
aan AES NNN 


Oe Ie a aos ne 0 GO 286 8.0 go. 4100 
: J, nx Clore 1 : 


HIE, 125; 























: 
ee 
e 
S 
'Z 
Deas 
COA 


















































There is a series of mixed crystals rich in manganese, the — 
last number of which is the saturated mixed crystal with 
about 4 per cent. of tin. SnMn, is less brittle than man- 
ganese and, when polished, has a surface like that of steel. 


Hardness, 4:5. SnMn, is similar in colour to the preceding 
C.M. 15 


996 CHEMICAL COMBINATION AMONG, METALS. 


compound and its hardness is 8—4. SnMn has a silvery 
white colour. These compounds are weakly attacked by 
acids. SnMn, is magnetic, SnMn, to a less degree, and SnMn 
least of the three. 

Tin-iron.—There ts doubt as to the occurrence of com- 
pounds of tin and iron. Levin and Tammann? and Isaac 
and ''ammann ? have studied the system and constructed a 
diagram (Fig. 126). Iron and tin do not mix im all propor- 
tions in the liquid state. At 1140°, between 32 and 79 per 
cent. of tin, two strata are found, one rich in iron and the 
other rich in tin. The greatest arrest due to crystallisation 
occurs at 32 per cent. of tin. At 893° between 10 to 93 
per cent. tin, arrest points occur. The mixed crystal y reacts 
with the melt contamig 79 per cent. of tin to form a 
compound. The thermal] effect is, however, small and shows 
no marked maximum. From 10 to 95 per cent. tin there 
occur at 780° further arrests which may be due to poly- 
morphic transformation in the compound formed at 893.° 

There is a distinct maximal arrest at 24 per cent. of tin 
which should correspond to a compound SnFe;. At 496°, 
between 35 and 97-5 per cent. of tin, arrests occur which, 
however, have not been explained. 

These alloys display notable magnetic properties ; the tin 
content has a marked influence on the temperature at which 
iron loses its magnetic permeability. 

Tin-cobalt—T wo compounds are formed between these 
metals, namely, SnCo and SnCo,. The system has been 
studied by Levkonja ? and Zemezuzny and Belynski.4 The 
results obtamed by these workers are in accordance. 
Levkonja’s diagram is shown in Fig. 127. The curve shows 
a maximum and a break, the maximum at 1150° and 33 per 
cent. of tin, corresponding to SnCog, and the break at 948° 
and 75 per cent. of tin, corresponding to the compound 


1 Zeit. anorg. Chem., 47, 141 (1905). 
2 Tbid., 58, 281 (1907). 

3 Tbid., 59, 298 (1908). 

4 [bid., p. 368. 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 227 


CoSn,! which undergoes a polymorphic transformation at 
520°. At 229° there are arrest points which are due to the 
eutectic between CoSn and pure tin. 

The compounds CoSn and Co,Sn are harder than their 


1500° 4. 


; \ fe; Sn : 
100° 
1300° Ze | . 
D> . : ‘ 
Sie Re oa Pe eles 
LV, 44 


1100° | -- GF Le oe WME, 


1000° 


MEZ 


7 AEE 4 


BWC WN 
a a = AN WAV, SS 


le Ay Wee 

nee Me Va v4 ve Wa YA4, 
gas C re é 

wl YW 




























































































Cala @ 
wal | WAAWWMMLA. 
o- 10 10 30 by O bs 60 bas fe oe 100 
Fig. 126. 


component elements. With regard to magnetic properties 
the cobalt-tin alloys may be divided into two groups ; up to 
50 per cent. of cobalt, magnetic properties are wanting ; the 
alloys containing more than 50 per cent. of cobalt are 
increasingly magnetic with increase of cobalt. 

1 The composition of this compound is indicated by the position of the maximal 


arrests at 948° and 520°.—T'ranslator’s Note. 
: 15—2 


228 CHEMICAL COMBINATION AMONG METALS. 


Tin-nickel.—Nickel combines with tin, and the following 
compounds have been shown to exist by thermal analysis : 





1500° | 





1400° 





Be 

ON Co, Sn ChSn 
130° \ 

\] 
1200° Hf ZL 





XK 
SS 
\) 











WNepe: 
Nantes | LHD >, 











E 
y 
“A 















































oO By 
oO © 
oO oO 
© Gg © 2 ¢ © (es ° ° 2 
Sap ee SS ye a ge (pa ae eae — 
— — si (Ses 
| 






































600 5 ‘ 
MMA 
500 Sem x < AQT 
400 yee NSS 
S a Sn SSE SAN 
Dot WANN BS 

200 = 

9) 10 20 “90 40 50 60 EO 80 20> 3t80 


ey Zum Clon ir & 
Fia. 127. 
NigSny, NijSn, and Ni,Sn. The diagram (Fig. 128) was 
traced by Voss.t. At the beginning of the curve mixed 
crystals separate. At 1135° and 82-5 per cent., eutectic 


1 Zeit. anorg. Chem., 57, 38 (1908). 


HOMOPOLAR INTERMETALL'C COMPOUNDS. 229 


crystallisation occurs. At 1162° and 60 per cent. of nickel, 
the compound Ni,Sn, is formed. From 64 to 42 per cent. of 
nickel a lack of miscibility 1s noted and two liquid phases 


14512 
o! Da We 
1400 Ni3Sn 



























































= G Ai, Sn 1 : 
ie aN <a Za 

100° a le Z Ye i 
veo i eS | ates Z ae : | 
800" ere WZ / Li Z 

v0 SRA 





SS 

BS 
oS 
Ze 
V 
ZA 
Z, 
ZY 











LE NASSASS 
: . Sn NN | 















































Fig... 128: 


occur. Another gap in miscibility occurs also between 
30 and 7 per cent. of nickel; these melts are in equilibrium 
with the compound Ni,Sn,. At 885°, arrests are noted 
between 85 and 60 per cent. of nickel with a maximum for 


930 CHEMICAL COMBINATION AMONG METALS. 


67 per cent. (by weight) of nickel, corresponding probably to 
the compound Ni,Sn. Microscopic analysis confirms the 
thermal data. 
Tin-platinum.—Platinum forms the following compounds 
with tin: SnPt,, SnPt, Sn,Pt,, and Sn,Pt,. The system 
was studied by Doerinckel! and is given in Fig. 129. SnPt, 





































































































2000" 
Pt;.S7 
Py PA S77 
1600° Y PLAS; 
Yy | | 
100° KK Pp 
= | 
1200° M9 ae DS 
GON: ZT [ - 
1000° as al ee i 
of}. 254 Prag 4 Pte Sn 
800 LMLE 
ft, | Sn Pt,Sn | Beams , 
600° Soe 
: PIS (ae ape 
400° bs XL, Sir, e De 
Pt Sn eo PtSa be (By /, 
Pt, SI, Ca id ~ we 
200° <l 
| Pt; 7 9 77 a 
Fie. 129. —>% in atomi 


is formed at about 1875° and 75 per cent. of platinum by 
reaction between crystals of platinum and the melt contain- 
ing 70 per cent. of platinum. Crystals of SnPt then begin 
to separate; the maximum occurs at 50 per cent. and 1281°. 
At 846° crystals of SnPt react with the melt of composition f. 


1 Zeit. anorg. Chem., 54, 35 (1907). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 281 


The arrests at this temperature show a maximum for 
about 40 per cent. platinum. According to Doerinckel this 
maximal arrest 1s due to the compound Sn,Pt,. A small 
difference between the position of the observed maximal 
arrest and that required for the compound may be explained 
by the formation of a layer around the crystals which hinders 
the completion of the reaction, as appears evident on micro- 
scopical examination. <A further series of arrests occur at 
738° with a maximum at 40 per cent. platinum; these 
indicate, therefore, a polymorphic transformation of the 
compound Sn,Pt,. At 587° this modification of the com- 
pound Sn,Pt, reacts with the melt having 5 per cent. of 
platinum, giving a compound at 28 per cent. of platinum 
which is probably Pt,Sns. 

The hardness of these alloys grows with increase of 
platinum content ; at 40 per cent. it 1s equal to that of cale 
spar, at 60 per cent. to that of fluor spar. Maximum hard- 
ness 1s found at 80 per cent., at which it is slightly greater 
than that of apatite. Mineral acids attack these alloys in 
inverse proportion to their platinum content. 


CERIUM COMPOUNDS. 


Cerium-bismuth. — These alloys have been studied by 
Vogel,! who noted the formation of the compounds BiCes, 
Bi,Ce,, BiCe, and Bi,Ce. The maximum (see Fig. 130), 
which is found at the high temperature of 1630°, corresponds 
to the compound Bi,Ce,, which requires a concentration of 
about 53 per cent. (by weight) of bismuth. At 1400°, as 
shown by microscopical analysis, Bi,Ce, reacts with the melt 
forming the compound BiCe,; which has an obscured maxi- 
mum at 82 per cent. of bismuth. This compound has its 
primary separation along B C and at 757° crystallises 
eutectically with cerium. Small thermal effects are noted 
between 830° and 860°, due to reactions between bismuth 
and small quantities of lanthanum and didymium present as 

1 Zeit. anorg. Chem., 84, 327 (1914). 


932 CHEMICAL COMBINATION AMONG METALS. 


impurities in the cerium used in the experiment. At 1525° 
and about 60 per cent. of bismuth, the compound BiCe is 
formed which separates primarily between 61 and 82 per 
cent. of bismuth. At 882° it reacts with the melt forming a 





«700 














Pah |, C 
46 00 ZL Se 
N 
BrCo ws B (7 
{300 t : V3 mal At | i 
a 
ie YZaZEN 
ee 
4300 NM 
x ! 
{100 \ 





Ze 
i oo ES 
: 





4190 


44 
A 








ISRRAAES 







































































LN 
1000 aN Ny 
NAN GE 
2 “ WN ae I 
Aa AY iS NG \ 
MARVANN NNN \ 
100 lie 
| ' 
' ' ' 
600 ; \ 
’ ' } 
| : 3 } 
500 . 
' u \ 
\ ! v4 
400 | L 
l : 
( } ' { VA 
300 t ; 
| ; BE G 
' 
200 _t wk de ae 
0 10 20 30 40 50 60 30 80 go 100 
Sa, ffs ~ pee By 


Fig. 130. 


compound richer in bismuth (Bi,Ce, requiring 74:8 per cent. 
bismuth). 

These alloys are very easily oxidisable ; exposed to air, 
they are quickly altered to a black powder and are energetic- 
ally attacked by acids. The hardness is greatest for 
medium concentraticns. 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 288 


Cervwm-iron.—These alloys, which are noteworthy for 
their pyrophoric properties, are known through the work of 
Auer von Welsbach.**"*? 


COMPOUNDS oF LEAD. 


Lead-bismuth.—It is doubtful whether chemical combina- 
tion occurs between lead and bismuth. The system has 
been studied by Mazzotto,? Kapp,’ Stoffel,> and Barlow.® 
The two branches of which the equilibrium curve consists 
intersect at 125° and 55 per cent. of bismuth. According 
to Kapp, the thermal effects corresponding to eutectic 
crystallisation occur from 36 to 98 per cent. of bismuth, 
which would show that up to 36 per cent. of bismuth solid 
solutions are formed. 

Lead-palladvum. — Palladium forms a number of com- 
pounds with lead, namely, Pb,Pd, PbPd, Pb,Pd,, PbPd, and 
PbPds;. Some doubt exists as to the occurrence of the last ; 
the first compound has been admitted to exist by Pushin and 
Paschsky,’ as a result of their measurements of the electro- 
lytic potential of these alloys. The system has been studied 
by Ruer,® whose diagram is reproduced in Fig. 181. Pb,Pd 
separates at 454° and 80-49 per cent. of palladium. This 
compound melts without decompesition. rom 40 to 75 per 
cent. of palladium, three series of arrests indicate three 


ELD hh, Pg 104,801 Gl00s). 

2 Vogel has recently published a paper on the alloys of cerium and iron (Zeit. anorg. 
Chem., 99, 25 (1917) ). He found that the metals are miscible in all proportions and 
form two compounds, namely, CeFe, and Ce:Fe;. The first is changed into the second 
at 773°; Ce.Fe; decomposes at 1085° into a liquid and a solid solution rich in iron ; 
the solution contains 15 per cent. of cerium and becomes poorer in this element on 
cooling. The compound CeFe, is magnetic, but loses its magnetic properties at 116°. 
It is not certain whether the second compound is magnetic. Pyrophoric properties 
are exhibited by these alloys, those with 70 percent. of cerium displaying this property 
to a most marked degree so that a slight scratch is sufficient to cause ignition. The 
compounds are hard and brittle; they are not oxidised at ordinary temperatures.— 
Translator’s Note. 

3 Memt. Ist. Lomb., (3), 7 (1886), and Nuovo Cimento, 18 (1909). 

4 Drud. Ann., 6, 754 (1901). 

5 Zeit. anorg. Chem., 58, 150 (1907). 

6 J. Am. C. S., 82, 1394 (1910); Zeit. anorg. Chem., 70, 183 (1911). 

7 Zeit. anorg. Chem., 62, 360 (1909). 

8 Lbid., 52, 347 (1907). 


234 CHEMICAL COMBINATION AMONG METALS. 


compounds, each of which on melting decomposes into 
a melt, and a new species of crystal. The first is formed 
at 500° and 50 per cent. of palladium and is the compound 
PbPd. The second compound is indicated by a weak 
maximal arrest at 595° and 56 per cent. of palladium ; the 
most probable formula is Pb,Pd,. The formule Pb.Pd,, 
Pb;Pd,, and Pb,Pd,; are less probable. The third compound 


“4 
“soot 








S 
RY 
RS 





nN 

















































































































1900 o 
1100° N 
\ pal 
1000" Ve 
WV, 
900 CZ PUPS 
AZ. 
800° x 2 
Sel ea ls vs Pa Pb, 
700° 
Pf P, < 
Ai |Z vA | 
‘uke 4! 
sf nus EB | ¢ 
400° ret J We a 
val ak. (PAA 
{ 
30¢ PH] 747 bys “Ps 
| ol Big SAIS 
Fat PO 
200° ok i wl Fe 
Ge NDS APSO SN SOY TINO es 5080) AOE $e. ply 100 
pig. 131, 


gives a maximal arrest for 67 per cent. of palladium at 830° ; 
here again the maximum is not well defined. The formula 
of the last compound should be PbPd,. The fifth and last 
compound, PbPdg, gives a maximum on the fusion curve at 
1230° and 75 per cent. of palladium. 

The hardness of these alloys is greater than that of lead, 
and increases up to about 78 per cent. of palladium, where it 
reaches a maximum (5), and afterwards decreases. Alloys 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 285 


with 27 to 74 per cent. of palladium are very brittle; the 
remainder are not so markedly brittle. 
Lead-platinum.—These metals combine to form a com- 
pound PbPt. The existence of two other compounds is 
doubtful. The system, of which the diagram is reproduced 
in Fig. 182, was studied by Doerimckel. At 40 per cent. of 


E. D 





1800 ° 


¢ 


Ft \P6b 





16C0° Ky 
ve 


woo LLL, 
ZR 


G00 ° > 


aves 
‘Bes n> 
LKEAL 



















































































400 SE CAE © LT EB 
ULATED 
5 ax r 
200 | ey ar 
OF ; 
O 10 20 30 LO 50 60 0 $0. 90 100. 





> ee cet COLo wei P 
Fi@4. 132. 


lead, crystals of platinum react with the melt of composition 
forming a compound which has not been well defined by 
thermal analysis. The irregularity of the thermal arrests 
lead to the supposition that the reaction does not proceed to 
completion on account of the crystals becoming coated with 
a sort of protecting covering, but microscopical examination 
has not rendered this certain. Between D and EH, a gap 
occurs. At the composition represented by D, a further 


2386 CHEMICAL COMBINATION AMONG METALS. 


reaction occurs at a temperature of 787°. The arrests show a 
maximum at 49-5 per cent. of lead which gives the formula 
of the resultant compound as PbPt. At 350° and at com- 
position C, a further reaction occurs whereby another com- 
pound may be formed, but its composition cannot be well 
determined on account of the reaction being incomplete as 
in the case of the first compound. Doerinckel! states that it 
certainly contains less than 40 per cent. of platinum. 

These alloys are harder than their components ; at 30 per 
cent. of platinum the hardness is almost equal to that of 
calc spar ; at 45 per cent. it 1s almost equal to that of fluor 
spar and increases up to 85 per cent. The alloys are easily 
oxidised and are attacked by nitric acid, those with less than 
50 per cent. of platinum being most easily attacked. 

Pushin and Laschtschenko ? have studied these alloys by 
making measurements of electrolytic potential and demon- 
strated the existence of two compounds, PbPt and Pb,Pt. 


Compounds of Metals of Group V. with Metals of the 
other Groups. 


COMPOUNDS OF ANTIMONY. 


—Antimony-manganese.—These metals combine, giving rise 
to two compounds, Sb,Mn, and SbMn,. The system was 
studied by Williams,? and its diagram is given in Fig. 133. 
It shows a very much flattened maximum and a discon- 
tinuity in the fusion curve. The maximum is at 66-9 per 
cent. of manganese and 919° and corresponds to the com- 
pound SbMn,. The discontinuity which occurs at 852° 
indicates the compound Sb,Mn, (60:3 per cent. Mn). The 
compounds form two series of mixed crystals, SbMn, from 
65 to 69 per cent. of manganese and Sb,Mn, from 50 to 60 
per cent. of manganese. They havea silvery-grey colour and 

1 Zeit. anorg. Chem.,. 54, 361 (1907). 


2 [bid., 62, 34 (1909). 
3 Ibid., 55, 3 (1907). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 2387 


resemble each other closely. On treating with 10 per cent. 
FeCl,, Mn,Sb, is more powerfully attacked than the other 
compound and assumes a deeper yellow colour. 

The two compounds are less hard than their components ; 
the hardness of the first is 8 to 4 and that of the second 2 to 8. 
The antimony-manganese alloys exhibit magnetic properties 
which, however, decrease with rise of manganese content. 
Sb,Mnzg is less magnetic than SbMnag. ° 


























7 mS 
777 ge 
WWD der 














LLL: LELEN EP LLNS NAS 









































° 10 Yo so 40 pe ve) jo ra) go 100 
Sean eee: 
Fig. 133. 


Antumony-iron.—I'wo compounds are formed, namely, 
Sb,Fe and Sb,Fe,. The system has been studied by 
Kurnakoff and Konstantinoff.t In the diagram (Fig. 134) 
the curve shows a discontinuity at about 732°, at which tem- 
perature arrests occur on the cooling curve. The compound 
indicated by these arrests is FeSb, (66-6 per cent. of anti- 
mony). ‘The other compound is indicated by a maximum at 
1014° and 41-17 per cent. of iron. It melts without decom- 


1 Zeit. anorg. Chem., 58, 1 (1908). 


238 CHEMICAL COMBINATION AMONG METALS. 


position. At the point C the equilibrium 3FeSb, @ Fe,Sb, 
+ 4S8b occurs. If the temperature falls below 732°, the 
compound Fe,Sb, forms, but considerable time is required 
for the completion of the reaction. Solid solutions are 
indicated from 41 to 46 per cent. antimony and from 95 to 


100 per cent. antimony. 
These compounds tend to occur in the labile state. 


1400 





{f0of 


a7) 

















- Uy, MN 
ie WN Sof, 
4000 WI); /, tp | Shale 





WWW) 

WN UP 

AUMMAAZOA 
mm AULA 



























































40a i \ESIG Ms 
YU 
600 je:) 
¢ 10 go 30 40 50 po gO Ga 400 
= % in atom fe 


Fig. 134. 


Antimony-cobalt.—T wo compounds are formed between 
these metals, namely, CoSb and CoSb,. The system has 
been studied by Kurnakoff and Podkapajeff,! and by 
Levkonja.2,_ The results obtained by these workers are 
generally concordant. The diagram (Fig. 135) is due to 
Levkonja. It shows a maximum at 1191° and 50 per cent. 
of antimony, corresponding to the compound CoSb. Between 


1 Journal Russ. phys.-chem. Soc., 38, 463 (1906). 
2 Zeit. anorg. Chem., 59, 305 (1908). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 289 


50 and 84 per cent. of antimony this compound reacts with 
the melt d forming the compound CoSb,. Arrest points at 
616° indicate the formation of an eutectic alloy. The alloys 
up to 67 per cent. of antimony show magnetic properties, 
which increase in intensity with crease in cobalt; the 
alloy with 90 per cent. of cobalt is most magnetic. The two 
compounds are, however, non-magnetic. 
Antimony-nickel.—The followmg compounds are formed : 
































ATE, 


LY, 
7, 











































































































lf 
Ts) 20 30 40 tO $0 ¥0 60 go 100 
Fig. 138 


Sb;Ni,, SbNi, Sb,Ni,, and SbNi,. The system has been 
studied by K. Losseff.t The curve (Fig. 1386) shows two 
distinct maxima. The first corresponds to the compound 
NiSb and occurs at 1158° and 50 per cent. of nickel; the 
second at 1170° and 72 per cent. of nickel indicates the com- 
pound Ni;Sb,. Begining at 4 per cent. of nickel, two arrests 
are observed ; microscopical analysis of these alloys show 
that at 50 per cent. and 612°, the compound NiSb reacts with 


1 Zeit. anorg. Chem., 49, 63 (1906). 


240 CHEMICAL COMBINATION AMONG METALS. 


the melt giving a compound whose formula is probably 
Ni,Sb;. The compound Nisb by addition of nickel forms a 
series of mixed crystals, of which the saturated mixed crystal 
is at 1072° and 56 per cent. of nickel. At 677° in alloys 
from 97 to 73 per cent. of nickel, a reaction occurs which 
gives a series of arrests having their maximum at 80 per 
cent. Microscopical examination reveals that at this tem- 
perature a new species of crystal 1s formed surrounding the 


1500 











aoe a 
acs a Ne. SE. 
Lp we ly | [Ma 





ie Weck ger 
y WI, 
WN, 


we); 
coh: | v WMA c_IA 


es 


B 











z 
S 
Boas 





~ 
° 
io) 
4 


















































tee go ad, in chee ce 100 

Fia. 136. 

saturated mixed crystals and separating them from the 
eutectic. The formula Ni,Sb corresponds to this compound. 
Above 677° it decomposes into two saturated mixed crystals 
containing 97 and 73 per cent. of nickel respectively. 

The compound NiSb has a red colour and is very hard and 
brittle. It dissolves in nitric acid, but is not attacked by 
hydrochloric and sulphuric acids or by strong _ bases. 
Ni;Sb, is harder than NiSb, but not so brittle ; it is finely 
granular and has the colour of fused iron. 


Antimony-palladium.—These metals combine to form the 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 241 


compounds Sb,Pd, SbPd, Sb,Pd;, and SbPd,. The system, 
whose diagram is shown in Fig. 137, was investigated by 
W.Sander.! The first compound separates at 30-7 per cent. 
(by weight) of palladium and about 670°, the second at 47 per 
cent. of palladium and 805°, the third at about 62 per cent. 
and 840°, and the fourth at 72-5 per cent. and 1220°. The 


























































































































{$00 = | 
A A 
1400 Ky 
AV 
{300 Jbl, . 
iW 
i were) + \ .% 
i PAIN 
ea vi 
ti Za 
400 ga ' ! 
ee as 
St Pa saa 
4Ou | \ ' 
er oe eae 
800 ff at: ~ AN ! : 
AWN NAY lee hee: 
ac ASSESS SY : Ges 7 
A , oo mae : 
600 TP VRE i = er 
Wie ee 
ae Wa ! Ba. ii ees Ee 
\ Paaate : 
(00 1 : eee sas ; 
é 10 10 30 Lo 50 60 20 go go 100 


———y aL mw pro Pol. 
Fig. 137. 


compound Sb;Pd; forms mixed crystals, on the one hand 
with palladium as far as 61-5 per cent., and on the other 
hand with antimony as far as 57-5 per cent. of palladium. 
At 733° the saturated mixed crystal forms the eutectic 
with PdSb. From 47 to 68-5 per cent. of palladium, arrests 
are noted from 525 to 532° with a maximum at 60 per cent., 
the arrests from 57-5 to 50 per cent. of palladium being at a 


1 Zeit. anorg. Chem., 78, 97 (1912). 
GM. 16 


942 CHEMICAL COMBINATION AMONG METALS. 


somewhat higher temperature than those between 60 and 
55 per cent. These thermal effects are acccmpanied by a 
change in structure of the alloys concerned. The mixed 
crystal corresponding to Pd;Sbg passes from an « to a 8 form 
without change of composition. The mixed crystals, richer 
in palladium, break up at a temperature which diminishes 
with increase of palladium into « Pd;Sbg, and a saturated 
mixed crystal. The formation of the compounds of 


1400 











ee ) ne ; | SEqiPt 
| A \ ». 
SNOOEION 











































































































(¢] 10 10 $0 ho 50 69 Yo 3 100 
agrees iy gas “Sb 
Fre. 138; 


palladium and antimony is accompanied by marked super- 
cooling. 

Alloys up to 72 per cent. of palladium are very brittle, 
particularly the mixed crystals of the compound Pd,Sb 
between 72-5 and 68-5 per cent. of palladium. 

Antimony-platinum.—These metals form the compounds 
Sb,Pt and Sb,Pt;. The existence of a compound SbPt is 
doubital The ee was studied by Friedrich and 
Leroux.! The diagram is given in Fig. 1388. A maximum 

1 Métall., 6, 1 (1908). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 248 


due to Sb,Pt occurs at 1280° and 66-6 per cent. of antimony. 
Another compound is shown on the curve nearer the anti- 
mony axis which crystallises peritectically. Friedrich places 
the peritectic point at 50 per cent. of antimony (SbPt). 

At 710° and at 752° and about 16 per cent. of antimony, 
thermal effects are observed probably due to the peritectic 
formation of other crystals rcund the crystals of platinum. 
Finally at about 28 per cent. of antimony, the compound 
Sb,Pt; 1s formed. Friedrich and Leroux have not dis- 
covered whether solid solutions are formed or not. 






























































































































































1600, 
1500 = =— sie! 
ws 
== 
wae Se 
4400 |} 
| peme  es Cx ,|Sb 
4300 Cee area 
aa | 
i Zee 
Sen ee 
eo Castes Sees Cx S| 
ae meee 
A100 a el en ee D>. V2 
hg 
4:00.0: i= eee = 
ge Mr 
BP 
gad ie es ee ee 
GES 
Joo pt es a, 
ra oe SS 
400 = ea Ze, 
SIE 
ade 10 10 Yo LO 50 60 40 80 30 -4o0 


grt OCterins, ob 
Fig. 139, 

Platinum dissolves antimony toa slight extent ; the actual 
limit of saturation is unknown because alloys with less than 
10 per cent. of antimony have not been examined. Anti- 
mony crystallises practically pure at the eutectic point 
lying near its own axis. 

Antimony-chromvum.—Antimony and chromium form two 
compounds, Sb,Cr and SbCr, as noted by Williams.! In the 


1 Zeit. anorg. Chem., 55, 8 (1907). 
16—2 


244 CHEMICAL COMBINATION AMONG METALS. 


diagram (Fig. 189) a maximum occurs at 501 per cent. of 
chromium and about 1110°, corresponding to the compound 
SbCr. At 675°, crystals of SbCr, formed by primary separa- 
tion, react with the melt forming at 82:96 per cent. of 
chromium, the compound $b,Cr. Both compounds form 


mixed crystals with the pure components. 
SbCr is very brittle ; freshly broken it has a dark grey 


1400 
{2CoF 


1000} f 


| 

U 

600} 1 
! 
' 
‘ 


1 


200 

















Bo7o. 10 90 60 60 6c 10 80 00 Py 
Fia@. 140. 


colour; it is easily attacked by dilute acids, assuming a 
Its hardness is 3 to 4. Sb,Cr has a silvery 
It is shehtly attacked 


Hardness 2 to 38. 


black colour. 
white colour and is as brittle as SbCr. 


by dilute acids, which turn it yellow. 


CoMPOUNDS oF BISMUTH. 
Bismuth-manganese.—Wedekind and Weit 1! have studied 
the capacity for combination of these metals and have 
obtained crystals of formula MnBi. 
1 Ber., 44, 2663 (1911). 


A study has also been 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 245 


made by Hilpert and Dieckmann.! The fusion diagram has 
been investigated by Bekier 2 and by Parravano and Perret.® 
The chief characteristics of the diagram as described by 
these authors are in fair agreement. The diagram is given in 
Fig. 140. The two metals are partially miscible in the liquid 
state and form a compound BiMn which, according to Parra- 


1£00 



























































ala ZIVLAZ VAL : 

Sos NE “itl 
LL 

s00 6 Mp LE ‘ 

ms Ae DP ° 

[ ALL) 

, LEZALE 












































Rie. 141. 


_vano and Perret, is formed peritectically at 400°. The curve 
is fairly simple; a gap in miscibility extends over the 
greater part of the diagram (from 80 to 93 per cent. of 
manganese). As the results are not at present clearly 
explained, it is unnecessary here to enter more minutely into 
a description of this system. 


1 Ber., 44, 2831 (1911). 
2 Int. Z. f. Metall., 7, 83 (1914). 
3 Gazz. Chim. Ital., 45, I., 390 (1915). 


946 CHEMICAL COMBINATION AMONG METALS. 


Bismuth-nickel—Two compounds are formed, namely, 
B'sNi and BiNi. The system has heen investigated by 
Portevin! and Voss.?. Fig. 141 shows the diagram of the 
system. The first compound separates at 437° and about 
25 per cent. of nickel, the second at 638° and about 50 per 
cent. of nickel. The separation of the compound BiNi from 
the melt and the reaction of the melt C with the mixed 
crystals rich in nickel take place with super-cooling, and the 
temperature of the reaction on the horizontal C' ¢ is conse- 
quently somewhat lower in practice than it should be. Voss, 
however, has some doubt as to the exactitude of the formula 
BiN1. 

Bismuth is only slightly soluble in nickel—not more than 
-5 per cent., while the solubility of nickel in bismuth 1s less 
than -5 per cent. The eutectic is very near the melting 
point of bismuth at about 270°. 


Compounds of the Metals of Group VI. with Metals of 
the other Groups. 


Chromium-iron.—Ilron forms a compound with chromium 
whose composition has not yet been well ascertained. The 
system has been studied by Treitschke and Tammann.? 

The fusion curve has an abnormal form. The magnitude 
of the thermal effects due to primary crystallisation 
diminishes slowly from iron to chromium. ‘The temperature 
at which the second arrest occurs sinks with increase of iron 
content up to 40 per cent. of iron and then rises up to the 
melting point of pure iron. The temperature of the third 
slackening in the cooling curves, which is at 1260° for melts 
with 50, 40 and 30 per cent. of chromium, is fairly constant 
and corresponds to an eutectic crystallisation. As im the 
case of iron-molybdenum, Treitschke and Tammann attri- 
bute the abnormalities to the slow velocity of formation of 

1 Q. R., 145, 1168 (1907). 


2 Zeit. anorg. Chem., 57, 52 (1908). 
3 Tbid., 55, 403 (1907). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 247 


the compound. While there is only a limited range of mixed 
crystals in the system iron-molybd num, chromium and iron 
form a continuous series with the compound which occurs. 
Chromium-cobalt.—-Chromium combines with cobalt, but 
the formula of the compound is not known with certainty. 
The system has been studied by Levkonja.t In the diagram 
(Fig. 142) there are noted at 1225° from 45 to 85 per cent. of 
chromium, distinct arrests ; they are, however, so small that 
it has not been possible to distinguish a maximal arrest. 
Chromium-nickel.—As in the preceding systems, 1t has not 


47005 





{500 LD Tne 
| Ge | Le 


ad TT 


1¢ 20 O Lo D0 OLY. « é O 
ms 3 om eee OUR 17 2 





















































1300 
0 90 100 


Fia@. 142. 


been possible hitherto to ascertain the nature of the chemical 
combination between chromium and nickel. The system 
was studied thermally and micrographically by Voss.? 

The diagram is given in Fig. 143. The two metals mix in 
all proportions in the liquid state, apart from a gap in 
miscibility between 42 and 45 per cent. of nickel. The curve 
is similar to that for chromium-cobalt and shows a minimum 
below 1300° and at 42 per cent. of nickel. The corresponding 
alloy, examined microscopically, shows an eutectic structure. 

Alloys with a high nickel content are hard even at high 
temperatures (500°), and are very resistant to chemical 
reagents. In nickel containing 2 per cent. of chromium the 


1 Zeit. anorg. Chem., 59, 325 (1908). 
2 Ihid., 57, 34 (1908). 


248 CHEMICAL COMBINATION AMONG METALS. 


temperature of magnetic transformation is lowered by 100° ; 
with 10 per cent. of chromium, nickel is non-magnetisable 
even at ordinary temperatures. 


COMPOUNDS OF MOLYBDENUM. 


Molybdenum-vron.—The system molybdenum-iron has 
been studied up to 60 per cent. of molybdenum by Lautsch 
and ‘T'ammann.! In this range, the metals form a compound 
whose formula has not yet been correctly ascertained. The 
fusion diagram shows irregularities. It has not the appear- 


1600¢ 
Ge 


ssool Up | 
4400 Uy 2D | ef Tt f 
ee 


1300 po 
























































age 1 2.0 50 10 50 60 0 $0.5. 90. -AOOZ 


Bige clas. 


ance of a normal binary system, but presents certain charac- 
teristics of ternary systems. As in the case of chromium- 
iron, it is held that a compound is formed whose velocity of 
formation and decomposition is small compared to the 
velocity of the changes produced in the melt by crystallisa- 
tion. In their study the authors distinguish between the 
ultimate composition of the melt referred to its components 
and the proximate composition determined by the concen- 
trations of the elements and the unknown compound formed. 

Molybdenum-cobalt.—Molybdenum forms with cobalt the 
compound MoCo. The system has been studied by Raydt 
and T'ammann.? The diagram (Fig. 144) shows that at first 


1 Zeit. anorg. Chem., 55, 388 (1907). 
2 Ibid., 83, 246 (1913). 


HOMOPOLAR INTERMETALLIC COMPOUNDS. 249 


mixed crystals separate along the curve 4 I’. The saturated 
mixed crystal F' contains 28 per cent. (by weight) of molyb- 
denum. At 1485° and 62 per cent. of molybdenum, the com- 
pound MoCo is formed. Below D B there separates either 
molybdenum or mixed crystals poor in cobalt. It is 
improbable that another compound richer in molybdenum is 
formed because the arrests at 485° only disappear near the 





| 










































































oO 10 20 30 40 50 6106 ATO v0 yo 100 
os vi on pre Mo. 


Fig. 144. 
molybdenum axis. The compound crystallises in long 
needles. 

Molybdenum-nickel.—The compound MoNi is formed 
between these metals as reported by Baar,! who has described 
cooling curves from 1600° to 700°. From 0 to 83 per cent. 
of molybdenum, mixed crystals separate ; from 338 to 49-5 
per cent., an eutectic separates, after the primary separation, 
composed of the saturated mixed crystal with 33 per cent. of 


1 Zeit. anorg. Chem., 70, 352 (1911). 


250 CHEMICAL COMBINATION AMONG METALS. 


raolybdenum and a compound which solidifies in dendritic 
crystals at 1840° from 49-5 to 54 per cent. of molybdenum. 










































































7000 
1400 
{Goo A 
A 
Foo aS 
RSS 
(Cow aa 
MoNi [ASS 
170 SS 
ory BS 
1400 GF a > 
| Min ISR nee 
4300 SS 
NW! 
1200 2 
; ae 
1100 , 
' ( t 
! ' 
4 4 
paar {ov 16 So 40 So 50 Jo FO go 10 


pe o ie peso Mo. 
Fr@. 145. 


The formula attributed to itis MoNi. From melts contain- 
ing 54 to 100 per cent. of molybdenum, there crystallise in all 
probability mixed crystals poor in nickel. 


G7 lel oad lat eta a 
HETEROPOLAR INTERMETALLIC COMPOUNDS. 


General Remarks. 


In this class we may include certain compounds which 
boron, carbon, silicon, phosphorus, arsenic, sulphur, 
selenium and tellurium form with metals. Such compounds 
are metallic in character, and in many respects must there- 
fore be studied together with the great category of chemical 
compounds between metals. Each of these classes of com- 
pounds has its own character, but general similarities in 
their properties necessitate their being grouped together. 
These compounds have usually a simple composition which, 
in the majority of cases, is related to the known saline 
valencies of their components; this regularity is rather 
apparent than real, because important exceptions occur 
among these heteropolar combinations, as will be seen in the 
following pages. 

Of the carbides, only those have been mentioned which 
show metallic properties, to however slight a degree. The 
thermal method has been applied in only a few cases, but 
where it has been possible to use this method of investigation 
the results have been striking, as in the case of the studies 
on steels. 

Those of the carbides which do not act upon water are of 
great importance in metallurgy, while those which can decom- 
pose water are of some theoretical interest. According to 
Moissan ! the carbides are of geo-genetic importance. Many 
elements combine easily with carbon, and a general regularity 


1 Moissan carried out the first notable researches on the carbides, using the electric 
furnace. Cf. Le four électrique. See also Les carbures métalliques, Paris, 1904 ; 
Ahrens, Die Metallcarbide—Chem.-techn. Vortrage, I. (1896), and O. Honigschmid, 
Karbide u. Silizide, Halle, 1914. 


252 CHEMICAL COMBINATION AMONG, METALS. 


has been observed which is worth mention. The elements 
of the even series of the periodic system react easily with 
carbon ; the elements of the odd serves either do not react or else, 
if they do, show a close analogy with the other metals of the even 
series. Sodium, magnesium, aluminium, copper, silver, gold 
and mercury, members of odd series, are exceptions. Only 
those compounds of the other classes will be noted which 
have metallic characters. All the systems hitherto studied 
will be described ; as was said above, the thermal method 
has greatly elucidated the question of the capacity for 
combination between heteropolar elements. 


CoMpouNDS oF Boron (BoriDEs). 


Boron-iron.—This system has recently been investigated 
by Hannesen.t The compound Fe;B, occurs, containing 
about 7-2 per cent. by weight of boron. Troost and Haute- 
feuille 2? had previously observed that iron contaiing about 
23 per cent. of boron became very brittle and unworkable. 
Hannesen’s observations only extend to about 8 per cent. 
of boron. Mixed crystals of iron 6 separate from 0 to 1-38 
per cent. ; from 1-38 to 4 per cent. mixed crystals of iron y 
occur, and from 4 to 8-5 per cent. there takes place the 
primary separation of the compound Fe,B,. Along A T 
(Fig. 146), we have the liquidus curve of the mixed 
crystals 6, and along B T, that for the y crystals. 

An eutectic occurs at B for 4 per cent. of boron, and then 
the curve rises from 1160° to a maximum at 1,3851° which 
is the melting point of the compound. 

The behaviour of boron with iron is i many respects 
analogous to that of carbon. 

Boron-nickel.—These alloys have been investigated ther- 
mally by Giebelhausen,? who observed the formation of four 
compounds, namely, Ni,B, Ni,B,, NiB and Ni,B,. The 

1 Zeit. anorg. Chem., 89, 287 (1914). 


2 ©. R., 81, 1263 (1875). 
3 Zeit. anorg. Chem., 91, 257 (1915). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 253 


diagram is shown in Fig. 147. Up to 8-5 per cent. of 
boron, the alloys consist of nickel and the compound 
Ni,B. The maximum for this compound is at 1225° and 
8-56 per cent. by weight of boron. N1,B crystallises only 
after super-cooling. At about 1165° and 11 per cent. of 
boron, Ni,B, separates, while at 1125° and 15-8 per cent., 
NiB is formed. Above 15-8 per cent. of boron, a new species 
of acicular crystals separates surrounded by the compound 










































































1600° 
MEST e— | 400" 
VP 
1 1 Ds, oa 1300° 
Ny | ONS 
AWNING 
xx a : : 100° 
: 1000° 
| 
H , I 900° 
l 
\ l 0 
A | g00 
ae G_ | bagge 
See iF 
Spe ae ee ee ee eee 
Fiaq. 146, 


NiB. Gniebelhausen gives to these new crystals the formula 
Ni,B3. It should be mentioned that the arrest due to secon- 
dary crystallisation dies out at 20 per cent. of boron, while 
the compound Ni,B; would demand 21-8 per cent. 

Alloys containing pure nickel have magnetic properties. 
The compounds are non-magnetic. The hardness of the 
compound Ni,B is less than that of quartz. The compounds 
richer in boron are, perhaps, a little harder, though not so 
hard as topaz. 


254 CHEMICAL COMBINATION AMONG METALS. 


COMPOUNDS OF CARBON (CARBIDES). 


Copper, silver and gold form compounds with carbon of 
the general formula R,C,.H,O (where R = Cu, Ag, Au). 
Such carbides, however, are not of a metallic nature. They 
are unstable and explosive. 

Beryllium, calcium, strontium, barium and magnesium 
form chemical combinations with carbon which are of great 


NiB NB 











1000 SEX 


























900 


Fig. 147 


theoretical and practical importance, but do not display 
true metallic characters. Mercury also forms an explosive 
compound of the formula HgC, . H,0. . 
Carbon-boron.— A carbide of the formula B,C was obtained 
by Joly (1893) and by Moissan (1894). This carbide is a 
black crystalline substance of specific gravity 2-51. 
Carbon-aluminum.—A carbide of the formula Al,C, was 
prepared by Moissan (1894) by melting kaolin with carbon 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 255 


in the electric furnace and by direct combination of alu- 
minium and carbon. In its properties this compound 
approaches the carbides of the alkaline earth metals. 

Carbon-titanium.—The compound TiC was obtaimed by 
Moissan in 1895. It is a crystalline substance of specific 
eravity 4-25 which does not act on steam even at 700°. 

Carbon-vanadium.—Alloys of carbon and vanadium are 
easily obtained in the electric furnace. Moissan obtained in 
1896 a carbide with 18-98 per cent. of carbon corresponding 
to the formula VC. 

Carbon-chromium.—Moissan (1894) by heating chromium 
with carbon in the electric furnace, obtained the compound 
Cr3C,, whose existence, however, 1s not yet confirmed. 

Carbon-molybdenum.—Moissan (1895) obtained a carbide 
of the formula Mo,C by heating molybdenum oxide with 
carbon in the electric furnace. 

Carbon-tungsten.—According to Moissan, tungsten com- 
bines with carbon at the temperature of the electric furnace, 
forming the compound W,C which contains 3-16 per cent. of 
carbon. Williams has described another carbide, more 
infusible than the preceding, of the formula WC. According 
to Bohm (1907), it is formed with difficulty, and he plainly 
throws doubt on its existence. 

Carbon-uranvum.—Moissan by heating uranium oxide 
with carbon obtained from sugar, obtained a carbide of 
metallic appearance of the probable formula U,C,. The 
same compound was obtained by heating metallic uranium 
with carbon. 

Carbon-manganese. — Troost and Hautefeuille (1875) 
reported the existence of the carbide Mn,C which is formed 
with great development of heat. Moissan (1898) and Leroux 
(1898) subsequently prepared this carbide. More recently 
Stadeler ! studied the system both thermally and micro- 
scopically. This investigation is of particular interest from 
a metallurgical standpoint, particularly since the introduc- 


1 Metall., 5, 260 (1908). 


256 CHEMICAL COMBINATION AMONG METALS. 


tion of manganese steels. Up to about 7 per cent. of carbon, 
the two components form mixed crystals ; at 6-72 per cent. 
of carbon, the carbide Mn,C separates. The melting point of 
manganese 1s raised by carbon up to 1280°, and a continuous 
series of mixed crystals is formed up to 4 per cent. of carbon ; 
the curve then descends to 1217°, which is the melting point 
of the carbide. 

A complete discussion of the system as far as it is known at 
present has been made by Guertler.t 

Carbon-iron.—The alloys of iron with carbon are of the 
sreatest historical importance both in theory and practice. 
It is not possible to allude here, even in passing, to the pro- 
perties of the various iron-carbon alloys or to describe the 
system iron-carbon as developed recently by the application 
of the principles of the phase rule. The subject is beyond the 
limits of the present work. The existence of various 
modifications of iron, all with different physical properties, 
complicates the study of the system. The two elements, 
which form isomorphous mixtures, also combine chemically 
forming the compound called cementite which has the formula 
Fe,C. The diagram has been discussed on the principles of 
the phase rule by Roozeboom.? 

Carbon-nickel.— Ruff and Martin (1912) have reported the 
existence of a carbide of the formula Ni,C. Beyond this 
nothing certain can be stated. 


COMPOUNDS OF SILICON (SILICIDES). 


Stlicon-lithiwm.—Moissan (1902—1903) prepared a silicide 
of the composition Li,Si or LigSi, by direct combination of 
the two elements. This is the only silicide of the alkali 
metals known. 

Silicon-copper.—Copper forms with silicon the compounds 


1 Metallographie, Vol. I., Part II., pp. 8 et seg. (1913). 

2 Guertler has devoted one volume of his Métallographie to these alloys. His account 
is the most complete and accurate which we possess at present of the subject. 

3 Zeit. phys. Chem., 34, 437 (1900); cf. also Contrib. a [ Etude des Alliages, p. 326 
et seq. 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 257 


Cu,5i and Cu, 5i4, the latter of which is to be reckoned as 
doubtful. The system has been studied by Rudolfit and 
Vigouroux.2 De Chalmet ? had previously reported a com- 
pound Cu,$i, and Lebeau,* Cu,Si. The diagram is given in 
Fig. 148. From -98 to 2:98 per cent. of silicon, mixed crystals 
are formed. At 849°, mixed crystals, a, are in equilibrium 


470 





4 


1100 | 


100 Dy 
1000 Dh 























«00 





{ 


~ 
Te 
r 
3 















































t) PY ee is] 11F3 1598 19,0 WLS 6.95 
—_—) of. eon Aipace ee 


Fie. 148. 


with a second species of mixed crystal, b, and with the melt B. 
From 7:34 to 8-3 per cent., this second series of mixed crystals 
occurs. At about 860° and 12-95 per cent. of silicon, the 
compound Cu,Si separates. Two reactions occur in the 
crystalline conglomerates; at 780 to 815°, the second species 


1 Zeit. anorg. Chem., 58, 216 (1907). 
2 C. R., 123, 318 (1896). 

3 J. Am. C. S. 18, 95 (1896). 

4 C. R., 141, 889 (1905). 


958 CHEMICAL COMBINATION AMONG METALS. 


of mixed crystal breaks up into the first species and a third 
species richer in silicon. At 710°, the latter species of mixed 
crystal decomposes, forming the first species and another 
kind of crystal which is the supposed compound Cuy9Siq. 
Rudolfi states that the compound Cu,Si reported by 
Vigouroux and De Chalmet corresponds to the eutectic HL 
(not shown on the diagram) and the compound Cu,i, to the 
eutectic C. 

The alloys of silicon and copper are very brittle; from 
8 to 100 per cent. of silicon they are easily powdered. The 
hardness increases with the silicon content. The colour 
varies from red and yellow to grey. Alloys contaiming small 
quantities of silicon—6:25 to 25 per cent.—are easily 
oxidised. 

Silicon-magnesium.—A silicide of the formula Mg,si is 
known and was prepared by Wohler in 1858. Gattermann 
(1889) obtained this compound by the action of magnesium 
on silicon. Winkler (1890), Vigouroux (1897), Moissan and 
Smiles (1902) and Lebeau (1908) have successively studied 
this silicide, which crystallises in greyish octahedra. 

Silicon-barvum.—A silicide, Badig, exists. Jacobs (1900) 
obtained a silicide by melting barium carbonate or oxide 
with silica in an electric furnace. Goldschmidt (1908) pre- 
pared this silicide industrially together with iron silicide. 
It has a greyish colour. 

Srlicon-strontium.—The silicide, SrSiz, was obtained by 
Jacobs (1900) by the same method as was described for 
barium silicide. 

Silicon-calcevwum.—The compound Casi, probably exists. 
The system has been studied by Tammann ? and its diagram 
is givenin Fie. 149. Arrests are noted at 990° from 38 to 82 
per cent. of silicon; the maximal arrest, at 60 per cent. of 
silicon, corresponds to the compound. The formula given 1s, 
however, not very well established since the reaction is never 
completed and Tammann was unable to note the duration 


1 Zeit. anorg. Chem., 62, 80 (1909). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 259 


of the eutectic crystallisation at 803° on account of the small 
heat of fusion of calcium. 

Alloys from 91 to 60 per cent. of silicon are slowly attacked 
by dilute acids, caustic alkalies and ammonia; the alloys 
from 88 to 52 per cent. of silicon are strongly attacked by 
these reagents. 

Sulicon-cerium.—A compound CeSi probably occurs, but 
the formula is not well authenticated. The system has 














Cae 


990 aN Conk Lee 
PaaS a SAY 

- - 

- 

a 10 20 30: me) $0 6b fo. 89 go 100 

— Fm prso 





Fw 
AX 
Ca 
SS 














——{ 


















































Fia. 149, 


been studied by Vogel,! but only up to 70 per cent. of cerium. 
Combination takes place at high temperatures with great 
evolution of heat. As the diagram (Fig. 150) shows, a com- 
pound is formed at 1530° and 16-4 per cent. by weight of 
silicon. The existence of the compound is also demonstrated 
by microscopical examination. The alloys are stable in air 
and unattacked by ordinary chemical reagents. They are 
hard and brittle. 


1 Zeit. anorg. Chem., 84, 323 (1914). 
17—2 


260 CHEMICAL COMBINATION AMONG METALS. 


Silicon-titantum.—Moissan, in 1895, by the action of 
silicon on titanic acid in the electric furnace, obtained a 
compound of the two elements. ‘Two silicides exist, Ti,Si 
and TiSi,. The first was obtained by Levy (1895) by allowing 
caseous titanium chloride to act on amorphous silicon heated 
to redness ; the second was prepared by Hoénigschmidt by 
a thermite method. 



















































































4600 Ce 

oe. 

ages. 

ee ¢ 
{400 Sea awe 

DA AN 
1300 SEE <i 

ae Ga ZK te 

4200 eS SY } ab 

t ‘s { gs. 

| hs | raf 

‘ a8 | am 
1400 : y r ee 

aa} ] on 

' Nea S 
4000 : ne ees 
900 Z 
3 fe) 10 40 30 40- SO §0 fo go Jo 100 

_ " wr [240 Se 
Fira. 150. 


TiSi, crystallises in tetragonal pyramids of an iron grey 
colour ; it is not oxidised in air and is unattacked by mineral 
acids except hydrofluoric acid. 

Silicon-zirconuum.— The silicide, ZrSi,, prepared by 
Hoénigschmidt (1906) and Wedekind (1900) is known. 
Zr$i, crystallises in rhombs and is stable in air. Wedekind 
(1910) obtained a colloidal solution of this silicide. 

Silicon-thorium.—Honigschmidt (1906) obtained ThSi, 
by action of silicon on thorium oxide in the electric furnace ‘n 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 261 


the presence of aluminium. It crystallises in dark grey 
lamelle. 

Stlicon-vanadium.—Moissan and Holt,! in reducing vana- 
dium oxide with silicon, believed they obtained the com- 
pounds V,Si and VSi,. The system has since been studied 
by Giebelhausen,’? who observed a maximum at 1655° and 


1700 ; 
V Si 


1600 


1500 








1400 


1300 














oe eae eee ee a 


fia. 151. 


47-5 per cent. of vanadium (see Fig. 151). This corresponds 
to the compound VSi,. The compound forms mixed crystals 
with vanadium but not with silicon. These alloys are very 
brittle; the long needles of the compound are readily 
separated by simple rubbing. It is hard enough to 
scratch silicon. 


1 C. R., 185, 78 and 493 (1902). 
2 Zeit. anorg. Chem., 91, 251 (1915). 


962 CHEMICAL COMBINATION AMONG METALS. 


Silicon-tantalum.—A silicide TaSi, is known; it was 
prepared by Honigschmidt (1907) by a thermite method, 
but not in the pure state. 

Silicon-chromium.—Four compounds of these elements 
are known, namely, Cr,81, Cr,5i, Cr,5i, and Crsi,. They have 
been studied by Moissan (1895), Zettel (1898), Lebeau (1903), 
and Vigouroux (1907). These silicides are all crystalline. 
Cr$i, crystallises in greyish needles having a metallic lustre. 

Silicon-molybdenum.—The compounds formed by these 
elements are Mo,Si, and Mosi,. ‘The first was obtained by 
Vigouroux (1899), the second by Hoénigschmidt (1907). 
Moissan (1895) had already observed that molybdenum and 
silicon could combine. 

Silicon-tungsten.—The two silicides W,Si, and WS$i, have 
been obtained by Vigouroux (1898), Defacqz (1907), and 
Honigschmidt (1907). They are grey in colour. 

Silicon-uranuum.—A compound USi, was obtained by 
Defacqz in 1908 by a thermite method. It is a metallic 
powder consisting of microscopic cubes. 

Silicon-manganese.—These alloys have been studied by 
Vigouroux,! Carnot and Goutal? and by P. Lebeau.? The 
last mentioned reports the formation of the compounds 
Mn,Si, MnSi and MnSi,. Actually, however, only Mn,Si 
and Mnsi are formed. A systematic study of the system 
was made by Doerinckel,* whose diagram is reproduced 
in Fig. 152. 

The melting point of manganese is lowered by addition of 
silicon, and from melts with 0 to 10 per cent. by weight of 
silicon, mixed crystals containing silicon separate. Between 
10 and 80 per cent. of silicon, the fusion curve shows a maxi- 
mum at about 21:3 per cent. of silicon and 1316°. This 
corresponds to the compound Mn,Si. Between 380 to 50 per 


1 Ann. Chim. Phys., (7), 12, 153 (1896) ; C. R., 141, 722 (1905). 

2 Ann. des Mines, (9), 18, 271 (1900). 

3 C. R., 136, I., 89, 231 (1903); Bull. Soc. Chim. (3), 29, 185 (1903) ; Ann. Chim. 
Phys. (8), I., 553 (1904). 

4 Zeit. anorg. Chem., 50, 119 (1906). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 263 


cent. of silicon, another maximum occurs at 33-75 per cent. 
and 1280°, indicating the existence of MnSi. It is probable 
that at 45 to 50 per cent. silicon and about 1165°, the fusion 
curve passes through a maximum, either free or obscured, 
and the author concludes that this would correspond to the 
compound Mnsi,. 

Stlicon-iron.—This system was studied by Guertler and 
Tammann,! who observed the formation of the compounds 
Fe,Si and FeSi. The diagram is shown in Fig. 158. The 
first compound separates at about 1240° and 88 per cent. of 


S 























aa 
AZZ > 
ve 
oe 
rf 
oA 
gg 
























































Fi@, 152. 


silicon, the second at about 50 per cent. and 1448°. From 
the maximum the curve falls to an eutectic at 76 per cent. 
silicon. Mixed crystals of iron and the first compound are 
formed up to 33 per cent. of silicon. 

The hardness of these alloys diminishes as the silicon 
content increases. The compound FeSi is a little less hard 
than silicon. Fe,Si is as hard as apatite. The alloys 
behave in different ways when treated with acids and 
alkalies. Thus, caustic potash attacks silicon strongly, but 
the two compounds and iron very slightly. Hydrochloric 


1 Zeit. anorg. Chem., 47, 163 (1907). 


964 CHEMICAL COMBINATION AMONG METALS. 


acid acts vigorously on iron, only slightly attacks Fe,Si and 
is almost without action on Fei and silicon. 
Silicon-cobalt.—This system has been studied by Lev- 
konja.t. Four compounds are formed, namely, Co,8i, CoSi, 
CoSi, and Co,Si,. The curve is shown in Fig. 154. Three 
of the compounds give maxima. ‘The first separates at 1327° 
and 19-5 per cent. by weight of silicon and shows a second 
thermal effect at 1204°. Between 19-4 per cent. and 


{$90 





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col WO 
wal 
pen elie NV 
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a, ar AY Oe oon de: 


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Fie. 153. 


32:5 per cent., there occurs another thermal effect with slight 
super-cooling below 1250°. The maximal arrest is at about 
24-8 per cent. of silicon. At this point the compound Co,Si, 
separates. A second maximum is found at 1395° and 
32-5 per cent. of silicon ; it corresponds to the compound 
CoSi. In the alloys between 32-5 and 49 per cent. of silicon, 
the CoSi of primary separation reacts at 1277° with the melt 
F’, forming the compound CoSi,. The third and last maxi- 

mum is at 1310° and 59 per cent. of silicon. 
Magnetic properties are observed in the alloys rich in 

1 Zeit. anorg. Chem., 59, 327 (1908). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 265 


cobalt, particularly in those containing less than 19 per cent. 
of silicon. 

Silicon-nickel.—The system was studied by Guertler and 
Tammann,! who revealed the formation of five compounds, 
Ni,81, Ni,9i, Ni,Si,, NiSi and Ni,Siz. Two of these com- 
pounds are indicated by distinct maxima. One of these is at 


































































































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ey facas ac 
Fie. 154. 


about 13809° and 33-3 per cent. of silicon, and corresponds to 
the compound Ni,Si. This compound forms a series of 
mixed crystals with nickel, having a gap from 11-6 to 27-6 per 
cent. of silicon. Only those alloys from 27-6 to 83-3 per cent. 
of silicon, however, have a homogeneous structure. Those 
with less than 27-6 per cent. undergo further transformation 
below the eutectic temperature, 1150°, so that their primary 
1 Zeit. anorg. Chem., 49, 93 (1906). : 


266 CHEMICAL COMBINATION AMONG METALS. 


structure is altered. The structure of alloys from 11:6 to 
27-6 per cent. varies according as the crystallisation occurs 
quickly or slowly ; in the former case the melt crystallises, 
in the latter case a new species of mixed crystals of composi- 
tion Ni,8i is formed. 

The second maximum, which occurs at about 1000° and 




















1500 R 
Z MS b 
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VL: se ee 
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=, SS / \ ine 
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o0PG 410 io $0. LO sO 00 to vO 90 {00 
SO lpr 
> 9 tu tame ve 
FIG: lbb, 


49-7 per cent. of silicon, corresponds to the compound Nisi. 
If the melts from 33-5 to 50 per cent. silicon are cooled 
quickly, the compound Ni,Si, separates at 40 per cent., while 
the excess of nickel remains as Ni,Si1. The formation of this 
compound is accompanied by a super-cooling of 10° to 25°. 
At 1017° and about 59 per cent. of silicon, there is a thermal 
effect ; a part of the separated silicon reacts with the melt 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 267 


of composition G, giving rise to a new compound to which the 
formula Ni,Siz; may be given. At 950° and about 60 per 
cent. of silicon there is a thermal effect which can be inter- 
preted as a polymorphic transformation of this compound. 

Alloys up to 22 per cent. of silicon are tough. At higher 
concentrations they become more brittle. They are similar 
to nickel in colour up to 15 per cent. of silicon, but thereafter 
tend to be yellowish, particularly the compound Ni,Si; the 
33 per cent. alloy is grey, the 40 per cent., reddish, and the 50 
per cent., again grey. The 55 per cent. alloy is greyish violet 
and the alloy with over 70 per cent. of silicon has the grey 
colour of that element. 

Alloys cooled slowly show a minimum of hardness at about 
15 per cent. of silicon. With higher silicon contents there 
is no difference between alloys cooled slowly and those 
cooled quickly. 

Silicon-ruthenvum.—Moissan and Manchot (1903) obtained 
a compound, RuSi, by melting the components in an electric 
furnace. It crystallises in very hard prisms. 

Silicon-platinum.—l'wo compounds, Pt,5i and PtSi, are 
known and were prepared in a pure state by Vigouroux 
(1896—1897) and by Lebeau (1907). The former compound 
is white, crystallme and very hard; the latter compound 
crystallises in silvery prisms. 

Silicon-palladium.—P. Lebeau and J. Jolibois (1908) by 
union of the two elements obtained the compounds Pd,Si 
and PdSi. The union of these elements occurs with evolu- 
tion of heat at a temperature of about 600°. Both com- 
pounds are dark grey in colour. 


PHOSPHIDES. 


Phosphorus-copper.—Copper and phosphorus form the 
compound Cu,P. The system has been studied by Heyn and 
Bauer.t. The diagram is seen in Fig. 156. Ata temperature 


1 Zeit. anorg. Chem., 52, 131 (1907). 


268 CHEMICAL COMBINATION AMONG METALS. 


of 1022° and at 14-1 per cent. by weight of phosphorus, arrests 
are noted which correspond to the compound Cu,P ; the 
presence of this compound has also been demonstrated by 
measurements of specific gravity and electrolytic potential. 
The alloys which have a concentration greater than 14 per 
cent. of phosphorus solidify with the formation of mixed 
crystals; from measures of differences of electrolytic 
potential it appears that they are formed of the compound 
Cu,P and a second compound Cu;P,. 








41100 FA 





eens 


TUM RN 


0 2 6 q 10 19 4h ‘CC 1.49 








oo 
SS 
SS 
os 


















































Fig. 156. 


Heyn and Bauer could not obtain alloys with more than 
15 per cent. of phosphorus, since with rise of temperature 
alloys richer in phosphorus lose this element by volatilisa- 
tion. At 1100° the limit Cis at 14-1 per cent. 

Addition of phosphorus increases the hardness of copper. 

Phosphorus-silver—The existence of phosphides of silver 
is probable, but their composition is not exactly known. 
Schrétter (1849) obtained a phosphide to which he gave the 
formula Ag,P,; Granger (1898) obtained a phosphide 
Ag P, and Emmerling (1879) reported a compound AgP. 

Phosphorus-gold.—Considerable doubt exists as to the 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 269 


phosphides of gold. Cavazzi (1886) obtained a compound 
AuP, Schrotter (1849), a compound Au,P,, and Granger 
(1898) observed the formation at 400° of a compound Au,P,. 

The solubility of phosphorus in gold 1s diminished at high 
temperatures. 

Phosphorus-magnestum.—The existence of the compound 
Mg,P., reported by Blunt in 1865, by Parkinson (1867), and 
Gautier (1899) is probable. Granger, however, believes 
that the compound Mg,P, is formed. 

Phosphorus-zinc.—The compound Zn,P, probably occurs, 
as reported by Hovsleff (1856), Renault (1866), Schrétter 
(1873), Emmerling (1879), and Jolibois (1908). The last 
named and Hovsleff also mention the compound ZnP, and 
Renault the compounds Zn,P, and ZnP.. 

Phosphorus-cadmium.—Cadmium and phosphorus pro- 
bably combine. Vigier (1861) and Renault (1878) report 
two compounds, Cd,;P, and CdP,. Emmerling (1879) 
mentions a phosphide which approximated to the formula 
Cd,P. 

Phosphorus-mercury.—These elements combine, according 
to Granger (1892), to form a compound to which he gives one 
of the formule Hg,P, or Hg,P,. 

Phosphorus-tin.—Phosphorus and tin combine together 
forming a compound with between 15 and 16 per cent. of 
phosphorus. Stead (1897) and Campbell (1902) have given 
the formula as Sn3P,, while Jolibois (1909) assigned Sn,P, to 
the compound. According to the last named, Sn,P, should 
give rise at 415° to a compound SnPs, corresponding to 40 
per cent. of phosphorus. On these data, Guertler? has 
constructed a fusion diagram for the system. 

Phosphorus-bismuth.—The existence of the compounds 
BiP and BiP, has been reported by Cavazzi (1884). 

Phosphorus-chromium.—Phosphorus forms in all pro- 
bability the compound CrP with chromium ; it was obtained 
by Rose (1832), Martins and Maronneau (1900). 

1 Guertler: Metall., 1, p. 917. 


270 CHEMICAL COMBINATION AMONG METALS. 


Phosphorus-tungsten.—The compounds formed by the 
combination of these elements were investigated by Defacqz 
(1900—1901), who reports compounds having the formule 
WP and WP, respectively ; they are not, however, well 
authenticated. 

Phosphorus-manganese.—The compounds MnP and Mn,P, 
are known. The system has been investigated by Zemcezuzny 
and Kfremoff,! and its diagram is given in Fig. 158. ‘Two 









































ESSN 
oy Sars 


Fie. 157. 


maxima and two eutectic points are exhibited. At 1890° 
and 28-57 per cent. of phosphorus, the compound Mn;P, 
separates. On the cooling curves, eutectic arrests occur at 
964°. Along the branch from 40 to 50 per cent. of phos- 
phorus, solid solutions are formed with a limiting concentra- 
tion of 44 per cent. phosphorus. The fusion curve could 
only be traced up to 47 per cent. of phosphorus, because 
beyond this concentration the phosphorus ignited. This 
arises from the circumstance that the compound is rather 
unstable and partially dissociates at high temperatures. 


1 Zeit. anorg. Chem., 57, 247 (1908). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 271 


This compound, from analogy with the corresponding 
derivatives of antimony and arsenic, has been given the 
formula MnP. From 10 per cent. of phosphorus the alloys 
have magnetic properties, which reach a maximum intensity 
at 28 to 30 per cent. of phosphorus (Mn;P,) and then decrease 
in intensity. 

Phosphorus-iron.—Iron and phosphorus form the com- 
pounds Fe,P and Fe,P. The system has been studied ther- 


(400 





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\\ m, P 
12.00 \ AN ! 
dD ANS : 


VAN 


es is 10 20 Me lo $0 
—— + m otra E. 














1000. 
































Fie. 158. 


mally up to a concentration of about 82 per cent. of phos- 
phorus by Saklatvalla,t by Gercke,? and by Konstantinoff.* 
In the diagram (Fig. 159) the first compound is indicated 
by a discontinuity in the curve at about 1185° and 25 per 
cent. of phosphorus. The second compound gives a maxi- 
mum at 1350° and 33:3 per cent. of phosphorus. By 
addition of phosphorus the melting point of iron is lowered 
to 1020° at 17 per cent. of phosphorus. Phosphorus forms 
1 Métall., 5, 321 (1908). 


2 Ibid., 604. 
3 Chem. Centr., I., 601, 1920 (1910) 


272 CHEMICAL COMBINATION AMONG METALS. 


solid solutions with iron y; the limit of saturation is at 
about 3 per cent. of phosphorus. At 610° Gercke noticed 
a thermal effect, which he attributed to a decomposition of 
these mixed crystals. 

Le Chatelier and Wologdine (1909) reported the existence 
of two phosphides, FeP, and Fe,P3. 




















1600 
1500 
Fe,P 
a ' 
Fe,P 
1300 
1 









































1200 
! 
100 NI 
! 
! 
! | | 
we Rea | 
| ( 

1 
| 
! { j 
! ' | 
goo l i ! 
(e) 10 40 50 


Atomic Percentage E 
Fig. 159. 
Phosphorus-cobalt—The compound Co,P occurs. The 

system has been investigated up to 40 per cent. of phos- 

phorus by Zemezuzny and Schepeleff.t The diagram 

(Fig. 160) shows that the compound Co,P, which melts 

without dissociation, is formed at 33-3 per cent. of phos- 

phorus and 1886°. On the cooling curves two other arrests 
1 Zeit. anorg. Chem., 64, 251 (1909). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 278 


are noted, one at 1022°, due to eutectic crystallisation, and 
the other at 920° and 8 to 33-3 per cent. of phosphorus, due 
to the formation of a modification of the compound. The 
compound is harder than cobalt and has magnetic properties, 
though to a smaller extent than cobalt and the intermediate 
alloys. 





{600 





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LD an 
7) = | 





-— 9 
n°) 

















“T/ 





Vdd 











1000 











LB =< Yel 














fe) 10 20 30 40 50 
Atomic Percentage P 
Fig. 160. 


Phosphorus-nickel—Phosphorus forms with nickel the 
compounds NigP, Ni;P, and Ni,P. The system has been 
investigated by Konstantinoff 1 up to a concentration of 35:5 
per cent. phosphorus, and the diagram is shown in Fig. 161. 
The melting point of nickel is lowered by addition of 
phosphorus. The eutectic point is found at 880° and 19 per 


1 Zeit. anorg. Chem., 60, 410 (1908). 
C.M. 18 


274 CHEMICAL COMBINATION AMONG METALS. 


cent. of phosphorus. Along B C the compound Ni,P 
separates ; at 23 per cent. of phosphorus and 960°, it decom- 
poses with formation of Ni,P,. The reaction, however, does 
not proceed to completion. The maximum for this com- 
pound on the curve is at 1182° and 28-3 per cent. of phos- 
phorus. A series of arrests at 1025° indicate a modification, 





{500 


a 








{30 Vj; 















































nlp, 
WY, fi 
NAP AN ae 
ye ] RS 
1100-4 ; 
oars < a 
Ce Y S| ! 
When ISS | 
1000 Sy Wy SQ 
i ey 
Le 
y ae 
gous UMA, Ni 
CELE DEL LNASN SV, 
‘gee 
mo 
Go 5 10 40 30 ob =e 





—> im aohme P. 
Fig. 161. 


a,of this compound. At concentrations above 28-4, these 
arrest points are lowered from 1025° to 1000°.. The maximal 
arrest occurs at 29-5 per cent. of phosphorus, and thereafter 
the arrests decrease until the ordinate of the compound 
Ni,P is reached. The compound Ni;P, in its @ form gives 
rise to solid solutions, while the a form does not. In the 
transformation from the 8 to the « form the solid solutions 
split up into a Ni;P, and Ni,P. This latter compound, 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 275 


which separates at 1110°, differs from the compound Ni,P, 
in colour ; Ni;P, is yellow, while Ni,P is steel grey. Ni,P is 
also distinguished by its long needle-like crystals. At 830°, 
arrest points occur which probably indicate an eutectic 
containing a compound richer in phosphorus and unstable 
at higher temperatures. 

Phosphorus-palladiwm.—According to Schrétter (1849) 
phosphorus and palladium form a compound PdP,. 

Phosphorus-wridium. ee (1848) also reports a 
compound IrP,. 

Phosphorus- ene or te to Schrotter the phos- 
phide PtP, exists, while Davy obtained phosphides of com- 
position between PtP and Pt,P. Clarke and Joslin (1883) 
report the existence of four compounds : Pt,P;, PPt,, PPt, 
and PPt,. Granger (1898) heated platinum in phosphorus 
vapour and obtained PtP, and Pt,P. Pt,P; should be a 
decomposition product. 


COMPOUNDS OF ARSENIC (ARSENIDES). 


Arsenic-copper.—These elements form the compounds 
CusAs and Cu,As,. The system has been studied by Hiorns,! 
Hiorns and Lamb,? Friedrich ? and Bengough and Hill (1910). 

The curve (Fig. 162) falls from the melting point of pure 
copper to an eutectic point at 685° and about 20 per cent. of 
arsenic. Friedrich observed the formation of solid solutions 
of arsenic in copper up to 4 per cent. of arsenic. The 
eutectic horizontal reaches as far as 25 per cent. of arsenic 
which corresponds to the compound Cu3As. At 26 per cent. 
of arsenic, another horizontal occurs at 710° which should be 
due to the formation of the compound Cu;Asy. According 
to Guertler * this horizontal represents a polymorphic trans- 
formation of the compound. It has not been ascertained 


1 J. Soc. Chem. Ind., 28, 451 (1909). 
2 Tbid. 
3 Metall., 2, 490 (1905). 
© Metall. Vol. I:, Part La, fp. 842. 
18—2 


276 CHEMICAL COMBINATION AMONG METALS. 


whether the two compounds form solid solutions. The 
existence of the compounds Cu,As and CuAs is doubtful. 

Arsenic-silver.—This system has been investigated by 
Friedrich! up to 25 per cent. of arsenic. It 1s not certain if 
the compound Ag;As is formed. The eutectic point has not 
been reached. At 528°, however, a horizontal was noted 
which is probably eutectic. 





1000 


| Cu (As 
yoo ‘ // Cup A, { J 1 






























































y//s 
a JN. 7 
UN NOD» 
/ 
Too Ld TIN \ 7 
J \\ 
y Wop ee 
ror eae === 
Sov 
400 ;4 
‘ aes ee 
Baa 10 Zo 30 40 50 
——_—> iy, bea love. As. 
Fig. 162. 


Arsenic-gold.—It is not certain if these elements combine 
with each other. Descamps (1878) obtained an alloy of 
composition Au,As;. Tivoli (1886) prepared a substance 
AuAs stable below 130°. 

Arsenic-magnesium.—These elements combine forming 
the compound Mg,As, obtained by Parkinson (1867). 

Arsenc-zinc.—The compound Zn,As, is probably formed 


1 Friedrich and Leroux, Metall., 3, 194 (1906). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 277 


by the union of these elements. ‘The system was studied 
thermally by Friedrich and Leroux,! and by Arnemann.? 
The data, however, do not go beyond 14 per cent. of arsenic. 

Arsenic-cadmium.—Two compounds are known, Cd,As, 





et IO) 


600) 








300 




















IO = 0 GO BO 360. 70 +802? BO 





Fiq. 163. 


and CdAs,. The system was studied up to about 56-4 per 

cent. of arsenic by Zemezuzny.2 The two arsenides of 

cadmium are fairly stable. Cd,As, melts at 721° and CdAs, 

at 621° (see Fig. 163). Arsenic is very slightly soluble in 
1 Metall., 3, 477 (1906). 


2 Tbid., 7, 201 (1910). 
3 Chem. Centr., 1913, IL., 2102, and Int. Z. Metall., 4, 228 (1913). 


278 CHEMICAL COMBINATION AMONG METALS. 


molten cadmium, and the melting point of cadmium is only 
lowered by 1-5° by addition of arsenic. 

The cadmium-arsenic alloys have also been studied by 
De Cesaris,t who established thermally the existence of 
the compound Cd,Asg,. 

Arsenic-mercury.—Ramsay ? prepared an arsenic amalgam 
by electrolysis of a solution of AsCl, using a mercury cathode. 
Vortmann,’ Partheil and Amort,* and Dumesnil* also investi- 
gated the arsenic amalgams. 

The existence of a compound of the formula As,Hgs, is 
probable ; it crystallises in yellowish-brown lamelle which 
are easily oxidised. 

Arseme-thalium. — It is not certain whether these 
elements combine with each other. Carstanjen (1867) 
obtained a soft alloy of the composition Tl,As. 

Arsenic-lead.—These elements probably form a compound 
PbsAs,. The system has been studied thermally up to 
34-4 per cent. of arsenic by Friedrich.’ He noticed the 
occurrence of two liquid strata, one rich in arsenic and a lower 
stratum of the compound. An eutectic point was observed 
at 293°. The data obtained were not sufficiently reliable to 
enable Friedrich to construct a diagram. 

Arsenic-tin.—Two compounds are known, Sn,As, and 
SnAs. The system was studied up to 50 per cent. of arsenic 
by Parravano and De Cesaris ‘ and by Jolibois and Dupuis.® 
Various compounds of tin and arsenic are described in 
chemical literature. Spring,’ by submitting arsenic and tin 
to high pressure, obtained an arsenide to which he gave the 
formula Sn,Asy. 

The diagram constructed by Parravano and De Cesaris is 


1 Rend. Soc. Chim. Ital., (2), 4, 196 (1912). 

2 J.C. 8., 55, 531 (1889). 

3 Ber., 24, 2764 (1891). 

4 Arch. Pharm., 237, 126 (1899). 

oC ds doa. 805 (1911), 

6 Metall., 3, 46 (1906). 

* Gazz. Chim. Ital., 42, I., 274 (1912); R. Acc. Lincei (5), 20, 593 (1911). 
CL R., 152, 1312-(1981). 

® Ber., 16, 324 (1883). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 279 


shown in Fig. 164. The melting point of tin is practically 
not lowered by addition of arsenic, and the curve rises from 
that point on the diagram, at first steeply, and then more 
slowly to the limit reached in the experiment. Three 
horizontals are found in the diagram which correspond to the 
compounds mentioned. The region of existence of the 
compound SnAs is somewhat restricted and the compound 
is dissociated on fusion. 


























Be Sn, As, 
600 ft | eos As 
“ aS 
Si As \ 
SOO | \ ; 
= 
Joo I 
Xn < \ 
Sn 00 90 go 70 60 Jo 


Fig. 164, 


Jolibois and Dupuis report the existence of two com- 
pounds, Sn,As, and SnAs. The thermal results obtained, 
however, are not very reliable. 

Arsenic-manganese.—The alloys of these elements have 
been studied by Dieckmann (1911), and by Friedrich and 
Schoen. Three compounds are formed, Mn,As, Mn3Asg 
and MnAs. 

The fusion diagram is given in Fig. 165 and shows three 
branches with two eutectics, one at 930° and 17 per cent. of 


1 Metall., 8, 727 (1911). 


280 CHEMICAL COMBINATION AMONG METALS. 


arsenic and the other at 870° and 43 per cent. of arsenic. 
At 1092° and 83-3 per cent. of arsenic, a maximum occurs 
indicating the separation of the compound Mn,As. The 
second maximum is at 930° and corresponds to the compound 
MnAs. The third compound should be formed at 40 per 
cent. and 760°. The curve could not be traced beyond 
50 per cent. of arsenic on account of the volatility of arsenic. 





eae 

| y/ Ma. bs 
hah 

LW 


| 
| 
Vee NY. me As 
MIB), 


























S02 





7-2 @ 4+ @ oe 





tou 
































Q 10 10 3o 40 so ¢o 
g . . 
—__— ip tu Ofornd As 


Fig. 165. 


A loys between 88 and 48 per cent. of arsenic are mag- 
netisable. Those richer in magnanese, after quick cooling, 
and those richer in arsenic, after slow cooling. 

Arsenic-iron.—This system has been investigated by 
Friedrich’ up to about 60 per cent. of arsenic. Up to this 
concentration, the followmg compounds occur: Fe,As, 
Fe,As,, FeAs and Fe,As, (?). 

From 1520° (see Fig. 166) the curve falls to an eutectic at 
840° between iron and the compound Fe,As, which latter 


1 Metall., 4, 131 (1907). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 281 


gives rise to a maximum at 920°. At 1080° the compound 
FeAs separates. Almost as soon as this compound separates, 
another thermal effect is observed at 1004°, Which reaches a 
maximum near the fusion curve. According to Friedrich, it 
corresponds to the formation of a compound Fe;As,. At 
799°, FeAs and Fe,As react with each other, giving rise to 
Fe, Aso. 





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fake) 
y e) 


Fie. 166, 


Arsenrée-cobalt.—The compounds Co,;As5, Co ,As, CogAs, 
and CoAs are known. The system has been studied by 
Ducelliez 1 and Friedrich,2 who have carried their observa- 
tions as far as mixtures containing 55 per cent. of arsenic. 
The compound CoAs corresponds to the maximum which is 
seen on the diagram (Fig. 167) at about 1175°. The other 
compounds separate between the maximum and the eutectic 


1 OC, R., 147, 424. 
2 Metall., 5, 150 (1908). 


282 CHEMICAL COMBINATION AMONG METALS. 


and give rise to discontinuities with which are associated 
three horizontals indicating thermal arrests. CozAs, 1s 
indicated by a maximal arrest at 1014° and about 37 per 
cent. of arsenic, Co,As by one at 960° and 33-3 per cent. of 
arsenic, and Co;As, by one at 920° and 28 per cent. of arsenic. 
At 830° another horizontal 1s observed which is probably 
due to a transformation of the last compound. Another 


‘0 





1400 


4400 v | 











1700 








1000 }, 


UCL S\\ 





















































70 90 wa So 60 
ae ere Tee a FW EE aan ik) 


Fra. 167, 

horizontal at 910° is probably due to a transformation of 
Co,As,. According to Friedrich, the horizontal at 830° 
should be attributed to a transformation of Co,As into 
another compound. 

Arsenic-nickel—T wo compounds are known, Bynes 
Ni,As, and NiAs, whose existence was inferred by Friedrich ! 
from a study of the system up to a concentration of about 
60 per cent. of arsenic. The two compounds are shown in 


1 Metall., 4, 207 (1907). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 283 


the diagram (Fig. 168) in the form of two maxima, one at 
1000° and 28 per cent. of arsenic, and the other at 965° and 
50 per cent. of arsenic. At 950° thermal effects are noted 
which are diagrammatically represented by a bow-shaped 
curve. According to Friedrich they are due to a new 
crystalline species which is formed on the one hand from 
Ni;As, and excess of nickel, while on the other hand Ni,;As, 





4300 
1400 7 
tf 
1300 tol: 
1Qa0 b+ LA 
YO 
1100 = Zz, pa 
: ' Ue ee MAs ( 


a7] f 
Tne 



























































fees 0 10 8 40 $0 6° 
——» Jom atom AS. 
Fiq. 168. 


is formed directly from the melt with an excess of arsenic. 
At temperatures between 500° and 600°, transformations are 
observed in the alloys below the eutectics. A new crystal- 
line species is formed which probably corresponds to the 
formula Ni,Aso. 

Arsenic-platinum.—The compound Pt,As,is known. ‘The 
system was studied by Friedrich and Leroux ! up to a con- 
centration of about 35 per cent. of arsenic. The diagram 

1 Metall. 5, 148 (1908). 


284 CHEMICAL COMBINATION AMONG METALS. 


constructed by them is given in Fig. 169. It consists of two 
branches intersecting in an eutectic point at 599° and about 
28 per cent. of arsenic. ‘The eutectic horizontal reaches on 
the one side as far as pure platinum and on the other as far 
as the concentration required by the compound Pt,Ass. 
Friedrich and Leroux did not obtain the compound PtAs, 


4F00% 





(}00 











1600 





{F00 











1400 


LS 


1300 























NUMAN 


MQQSs3o SS 









































500 


Fie. 169. 


prepared by other workers on account of the considerable 
loss of arsenic which took place from melts containing more 
than 30 per cent. of that element. 


CoMPOUNDS OF SULPHUR (SULPHIDES).? 


Sulphur-rubidium.—Sulphur combines with rubidium, 
forming the compounds Rb,Ss, Rb,S4, Rb,S; and RbaS¢. 


* The compounds mentioned here are those studied thermally ; many well known 
sulphides are of course omitted ; they are described in any modern work on inorganic 
chemistry. 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 285 


The system has been studied by Biltz and Wilke-Dé6rfurt.1 
The curve (Fig. 170) shows only one maximum, which corre- 
sponds to the pentasulphide, the other three compounds being 
marked by discontinuities. Four thermal horizontals 
between the compounds are also noted. The first compound 
is formed at 200° and 86 per cent. of sulphur, the second at 
160:4° and 42:8 per cent. of sulphur, the third at 280° and 
48:3 per cent. of sulphur, and the last at 206° and 53 per cent. 
of sulphur. The tetrasulphide decomposes below its melting 














Fb;S, Rb,S, Ab,S; 


i, | | | 
27) } H ! J 1 L I it it 1 i t 1 4 4 1 L 


Hb S¢ 











4 rr rT 34 5 36 37 38 39 GO ut 42 43 44 45 46 Wf 48 49 50 51 52 SF SY 95 56 57 100 
RiGee leo: 


point. The hexasulphide is characterised by an obscured 
maximum between 538 and 54 per cent. ‘There is a rise in 
temperature of 200° on the fusion curve between the bi- 
sulphide and the trisulphide. It cannot be said with cer- 
‘tainty whether a third compound 1s formed from these com- 
pounds or whether a polymorphic transformation of the 
bisulphide occurs. To obtain the crystallisation of the 
compounds Biltz and Wilke-Dorfurt had recourse to inocula- 
tion of the fused mixtures. | 

The alloys formed varied in colour from red to chestnut 
red. 

1 Zeit. anorg. Chem., 48, 314 (1906). 


286 CHEMICAL COMBINATION AMONG METALS. 


Sulphur-cesium.—The compounds Cs,S.,, CsS3, Sso5y4, 
Cs,5;, and Cs,8, are formed by the union of these elements. 

This system was also studied by Biltz and Wilke-Dorfurt.4 
The curve (Fig. 171) is similar to that for rubidium-sulphur. 
It shows a maximum at 37-6 per cent. and 210° and two dis- 
continuities, one at 32-5 per cent. and 160° for the tetra- 
sulphide, and the other at 42 per cent. and 183° for the 
hexasulphide. The trisulphide has an extended but indeter- 
minate region of existence so that it can only be identified 
by the change in the eutectic horizontals at 205-5° and 151°. 





0+ 7 
170 L — —— + ——— > ———— 
160 4 











tee - - --e 
een ee 
130- AES Sa ey OE oe 
Hot a,s, © as 0525, OS, 4 
130 1 . 1 1 pg Pie ie See et ee ee 1 L 1 ‘ 1 n 1 1 
4 22 2 % 2§ 26 27 8 29 3 J $2 33 3 3F 86 37 398 39 46 Gf 42 43 44 46 CB 47 10 
7 
Fig, ATI; 


As in the preceding system it was necessary to seed the fused 
mixtures to start crystallisation. The alloys are similar in 
colour to those of rubidium. 

Sulphur-copper.—The compound Cu,§ is formed. ‘The 
system has been studied by EK. Heyn and O. Bauer ? and by 
Friedrich (1908). The melting point of the sulphide was 
found by the first two workers at 1127° and by Friedrich at 
1185°. Friedrich also noticed that the liquidus curve was 
lowered by further addition of sulphur (Fig. 172). On 
melting sulphur with copper, two liquid layers are formed, as 
was noticed by Mourlot (1897), and later by Heyn and Bauer. 


1 Zeit. anorg. Chem., 48, 316 (1906). 
2 Metall., 3, 76 (1906). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 287 


The upper layer contained 85 per cent. of the sulphide, while 
the lower layer was rich in copper and only contained 9 per 
cent. of the compound. Solid solutions were not observed 
to occur. 

Sulphur-silver—The compound Ag,S occurs. The alloys 
of silver sulphide and silver have been studied by Rossler 
(1895), Pélabon! and Friedrich and Leroux.? Thermal 
analysis showed that the compound melted at 812° and that 
at 906° a monotectic horizontal occurred (see Fig. 178). ‘The 





4300 


1200 


' 
1000 T 
‘ 
‘ 






































c to 4 30 40 
aD nA Onda. Ae 


ETGy- U72: 


occurrence of two liquid layers in the fused state was also 
observed. Of these liquid strata, the lower contained the 
sulphide mixed with silver, while the upper contained no free 
silver. Friedrich and Leroux observed at 175° a transforma- 
tion of the silver sulphide. It is probable that solid solutions 
of sulphur in silver occur. 

Sulphur-gold.—These elements combine directly with 
difficulty ; 1t appears, however, that the compound Au, 1s 
formed which was obtained by McLaurin (1896). 

Sulphur-bismuth.—The compound Bi,8; is known. The 


1. R., 148, 294 (1906). 
2 Metall., 365 (1906). 


288 CHEMICAL COMBINATION AMONG METALS. 


system has been studied by Aten,! and by Pélabon,? who 
reports that at 760° and 50 per cent. a compound BiS 
separates. The existence of this compound is, however, 
denied by Aten, who states that the curve from +1 to 52:4 per 
cent. of sulphur is simply the fusion curve of a single sulphide 
containing more sulphur than BiS—probably Bi,8,. The 
study of the system has not been carried beyond 55 per cent. 
of sulphur because at this concentration the mixture boils at 
its melting point, 1.e., the melting point and boiling point 


Ato) 
Yt AEN Sat 





WAAAY 


AN 


- = 


Sa 


1000 





























(oe) 
5 N 
‘ 
ae 
ate ee 
( 
{ 
pee 10 70 40 LO 





Sees i) iy Welonee Os 
Fig. 173, | 
curves intersect. The compound Bi,§, is partially disso- 
ciated in solution since it produces sulphur vapour. 
Sulphur-indium.—The compounds In,$3, In,8, and Ins 
are formed, of which the first two were reported by Thiel 
(1904) and the last by Thiel and Koelsch (1910). 
Sulphur-thallium.—The sulphide TI,S exists and, as 
Bessler (1895) observed, it combines with sulphur. Pélabon * 
has followed the curve of fusion. At 448° and the concen- 
tration of the compound a maximum is observed. Between 
the sulphide and pure thallium two immiscible melts occur. 
1 Zeit. anorg. Chem., 47, 387 (1905). 


2 Journ, Ch. Phys., 2 320 (1904). 
3 ©, R., 145, (118) 1907. 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 289 


With increase of sulphur the curve falls rapidly from the 
maximum. At a concentration corresponding to TI,S, the 
curve passes through 125°. Pélabon’s data are, however, 
incomplete. 

Sulphur-tin.—These elements combine, forming the com- 
pound Sns. ‘The system has been studied by Biltz and — 
Mecklenburg.t The diagram is given in Fig. 175. The 


}00 os, Gees 


es « SS 
NNN 
Ss 
XS 














foo 





400 Sc Pe eS 
SASS“ 
2 Ee SN 


3oo 








100 
































gee caewer 


Rig: 174, 


compound is formed at 881° at a concentration of 21-6 per 
cent. of sulphur. From the maximum representing the 
compound the curve descends on the left, at first rapidly and 
then slowly, so as to appear almost horizontal, as if to indicate 
a lack of miscibility in the liquid state. This, however, is 
not the case as the boiling point curve above 1200° shows. 
The curve then descends almost vertically to the eutectic 
point, which is practically coincident with the melting point 
of tin. The existence of two distinct strata in solid mixtures 


1 Zeit. anorg. Chem., 64, 231 (1909). 
C.M. ; 19 


990 CHEMICAL COMBINATION AMONG METALS. 


may be noted, due to the great difference in the melting 
point and specific gravity of the components. The curve on 
the other side of the maximum descends, but has only been 
followed for a short distance on account of the volatility of 


the free sulphur. 
Sulphur-lead.—Sulphur and lead form the compound PbS. 














EiIGz 175: 


The system has been studied by Friedrich and Leroux.! 
From the diagram (Fig. 176) it appears that by addition of 
sulphur the liquidus curve rises almost vertically. At 1150° 
a short horizontal tract is noticed. The melting point of 
the compound is at about 1120°. Two liquid layers are 
formed. 

-Sulphur-arsenic.—The two compounds As,S, and As,S, 


1 Metall., 2, 536 (1905). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 291 


are known. ‘The former melts at 320° and is dissociated in 
the fused state ; the latter melts at 310° and is undissociated 
even at boiling temperature. The system has been studied 
by Jonker t and Borodovsky.? 

The diagram constructed by Jonker is shown in Fig. 177. 
It shows that solid solutions do not occur between As,S, 
and sulphur, which is due to the fact that the liquid mixtures 
































PAs 

: Sy 
ise SSNs 
“| LASS 
TRAN 
538 SS RS SS 
ol SRS 
SES ESSN 
= RSS 
SAX s““Q“—“q“s 
































°o 10 to 40 40 50 6¢ 


SS a im pe eee OG f 
Fic. 176. 


are exceedingly viscous. ‘The same is the case between 
As,S, and sulphur. Jonker has carried out viscosity 
determinations and has observed that the viscosity 
diminishes slowly at high temperatures. The existence of 
other compounds is not certain. As,S; may be formed from 
60 to 80 per cent. of sulphur. 

Borodovsky’s results are not in concordance with those of 
Jonker. He gives the melting point of As,S, as 808° and 


1 Zeit. anorg. Chem., 62, 89 (1909). 
2 Rend. Soc. Chem. di Dorpat, 14, 159 (1906). 
19—2 


292 CHEMICAL COMBINATION AMONG METALS. 


the eutectic point as 225°. The curve then rises and shows a 
discontinuity at about 300°. 

Sulphur-selenuum.—The two components are completely 
miscible in the liquid state. The existence of the compound 
Se,5 1s doubtful. The system has been studied by Ringer. 
From his diagram it appears that solid solutions of sulphur 
in selenium occur up to 13 per cent., and of selenium in 


616°) 


5P4 ° 








As+bL 


J21° 




















370° } eS 
feed Een Nj 
Ny 
* 
‘, 
N 
* KY 
ne 
« 
N) 
S: 
e \ 
wud 111° 
v 5 
As As, 5S, As, S, S 
-_— mol % AY 
FIG). 177, 


monoclinic sulphur up to 27 per cent. The solubility of 
selenium in rhombic sulphur is but small. An intermediate 
crystalline species occurs between 18 and 50 per cent. _ 
Sulphur-molybdenum.—The compounds Mo,§, and Mos, 
occur ; they were obtained by Guichard (1900) ; the second 
is formed by heating the first compound. 
Sulphur-manganese.—Manganese combines with sulphur, 


1 Zeit. anorg. Chem., 32, 202 (1902). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 293 


but little is known thermally. The compound Mn§ is 
probably formed. The manganese sulphides have been 
studied by Le Chatelier and Ziegler (1902). 
Sulphur-vron.—The compound Fes occurs. The system 
wron-iron sulphide has been studied by Treitschke and 
Tammann? and by Friedrich.2. These workers deny the 
existence of compounds between FeS and pure sulphur. 


1600 





meek 





14OO |} 
‘ 


sal AZ Dy bs 


WK 


ph WAS 5 7 SEF ATES ABP A AAD EP GI 1. SR 
1 















































ee ae 
Fig. 178. 

The sulphide and sulphur mix in all proportions in the liquid 

state; from the liquid mixtures, FeS and iron probably do 

not crystallise in the pure state, but « Fe absorbs small 

quantities of FeS (less than 1 per cent.). Whenever small 

traces of the oxides or silicates of iron are present a lack of 

miscibility is noticed in the system, and about 60° below the 

eutectic arrest an arrest is noted which has its maximum at 
the eutectic composition. 

The equilibrium diagram (Fig. 178), due to Tammann and 


1 Zeit. anorg. Chem., 49, 320 (1906). 
2 Metall., 7, 257 (1910). 


294. CHEMICAL COMBINATION AMONG METALS. 


Treitschke, represents the system Fe-FeS in presence of iron 
oxide. In addition to the lack of miscibility two slackenings 
are noticed, one at 970° and the other at 910°, with the 
inmaximum duration at the eutectic composition. In the 
presence of oxide of iron the quantities of FeS which dissolve 





4500 


ae 
Ui, 
U/L) 


{200 


{900 











aS 
= 
SS 

va 
S 








Ne 
— 
oS 












































goo Hf : y, \ 
Va MA AWAD GV BS IN 
go00 £ ; 
ee | 
Joo 5 10 ALB 30. 40 3 fo... 60 
—_—$ a 1 Forrrr Lt 
Fig, 179, * 


in Fe-y are greater and a lowering of the transformation 
point into Fe-8 is produced. Also, iron sulphide does not 
show the transformation which, in the absence of oxide, 
takes place at 298°. 

Iron containing sulphur becomes brittle on heating, even 
when less than -02 per cent. is present. In the cold it is 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 295 


brittle with about -5 per cent. of sulphur. ‘The brittleness is 
due to the presence of lamellz of iron sulphide intercalated 
between the crystals of iron. 

Sulphur-cobalt—According to Friedrich? the compounds 
Co,S3, Cog54, Cogs; and CoS are probably formed. The 





1LO6 


Y 
. Yip 






























































Yoo U, 7 7 “yy hl \ 

Mh ee Gg, LV AN \ 

208 5er +0 20 0 LS fo 
sees ry erp er 


existence of the last three is not well authenticated. The 
curve (Fig. 179) shows an eutectic point at 40 per cent. 
Although this corresponds to the composition of a compound 
Co,8,, the alloy is really an eutectic mixture, as is revealed by . 
microscopical examination. At 930° a discontinuity occurs 
on the curve at a concentration corresponding to the formula 
Co,S3. This crystalline species, which is formed at 790°, 


1 Metall., 5, 212 (1908). 


296 CHEMICAL COMBINATION AMONG METALS. 


decomposes into another species to which in all probability ~ 
the formula Co,5, belongs. At about 50 per cent. of sulphur 
a flattened maximum is observed corresponding to the com- 
pound CoS. Solid solutions of sulphur in cobalt do not 
exist to any measurable extent. 

Sulphur-nickel—The compounds Ni,5,, Nig5; and, pro- 
bably, NiS occur. The system has been investigated by 
Bornemann,* and the diagram is shown in Fig. 180. From 
the melting point of nickel the curve falls to an eutectic point 
at 644°. This point occurs at 33-3 per cent. sulphur, but, 
as shown by microscopical analysis, no compound occurs. 
At about 785° and 40 per cent. of sulphur Ni,8, separates ; 
it decomposes at 532°, giving another crystalline species ; 
this in turn undergoes a decomposition at 520°, giving a com- 
pound with the probable formula Ni,5;. The curve was 
followed by Bornemann up to 45 per cent. of sulphur. In all 
probability, as Guertler 2 observes, the compound NiS is 
formed at about 900° and 50 per cent. of sulphur. 

Sulphur-palladium.—The sulphide Pd,S obtained by 
Schneider ? and Réssler (1895) exists. 


COMPOUNDS OF SELENIUM (SELENIDES). 


— Seleniwm-copper.—The system copper-copper selenide has 
been studied by Friedrich and Leroux.* The existence of 
Cu,Se is revealed. The maximum, as is seen from the dia- 
oram (Fig. 181), is at 11138° and 33-3 per cent. of selenium. 
At 1068° there is an eutectic horizontal which reaches from 
the composition of the compound to that of pure copper. 
Friedrich and Leroux report a tendency to the formation 
of strata. Guertler® also reports the existence of a com- 
pound CuSe whose melting pomt would be found to be much 
lower than that of the first compound. 

1 Metall., 5, 13 (1908). 
2 Metallographie, Vol. I., p. 986. 
3 Pogg. Ann., 141, 530 (1870). 


4 Metall., 5, 355 (1908). 
5 Metallographie, Vol. I., Part I., p. 953 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 297 


Selenvum-silver.—The system silver-silver selenide has 
been studied by Friedrich and Leroux.) A study has 












































1300 
1200 
\\ ! 
\ \\ Git ie 
NN . 
4N0O - IN is 
{O00 a 
] 
Goo 4 
(3) 10 2O 30 LO 50 
- i cy OA Sad fe 
Fie. 181. 


also been made by Pellini.? Fig. 182 is the diagram con- 
structed by the last named. From the melting point of 





1100 — | j 


NING 


ie SS‘ 
IS 
30 SQ 





as i ca 
PA 
































900 Pf 
100 nN 
Vf 
/} 
ae oO 10 2Qo 50 HIG) 
_>—_— i m4 Olorues has 
Fig. 182. 


selenium (217°) the curve rises rapidly to 696°, and remains 
horizontal from 5 to 52 per cent. of silver, rising then 


1 Metall., 5, 355 (1908). 
2 Gazz. Chim. Ital., 45. I., 533 (1915). 


298 CHEMICAL COMBINATION AMONG METALS. 


to 897° and 66°6 per cent. of silver, the maximum cor- 
responding to the compound Ag,Se. The curve falls and 
then rises to 890° and remains horizontal from 68 to 89 per 
cent. of silver, rising thence to the melting point of the metal. 
The two horizontal tracts represent gaps in miscibility. At 
122° at all concentrations, arrest pots are noted which are 
due to a transformation of the compound Ag,Se.  Pellini 
performed his experiments in an atmosphere of nitrogen. 

Selenvum-zinc.—Rio (1828) found a compound ZnSe, 
combined with HgS in a mineral from Mexico. Fonces- 
Diacon (1900) by heating zine chloride in hydrogen selenide 
obtained the compound ZnSe in crystalline form. 

Selennum-cadmium.—Margottet (1877) obtained from cad- 
mium and hydrogen selenide the compound CdSe, prepared 
also by Fonces-Diacon (1901). 

Selenvum-mercury.—This system has been studied by 

Pellini.t The compounds Hg,Se and Hegde are formed ; the 
latter can be distilled without decomposition. The highest 
temperature at which the distillation can be performed is 
from 600 to 650°. From 500 to 650° the mixture is semi- 
liquid. From 132° to 139° an arrest 1s observed due to the 
solidification of selenium after super-cooling. 
— Selenvum-vndium.—According to Thiel and Koelsch (1910) 
these elements form a compound In,Se3. The existence of 
another compound poorer in selenium is also probable. 
Indium and selenium mix with a brisk reaction, giving a dark 
liquid. | 

Selenvum-thalium.—tThe system has been studied by 
Pélabon.2, The compounds Tl,Se, TlSe and TI,S,; are 
formed. The fusion curve, leaving the melting point of 
thallium (802°), runs at first horizontally at 400°. Corre- 
sponding to this horizontal tract two liquid layers exist, the 
lower of pure thallium and the upper a mixture of Tl,Se 
and selenium. ‘The curve then falls to an eutectic at 23 per 


1 Rend. Acc. Lincei, 18, II., 211 (1910) ; Gazz. Chim. Ital., 40, 44 (1910). 
2 C. R. 145, 118 (1907). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 299 


cent. of selenium, from which it rises again to 838°, where a 
maximum corresponding to the compound TlSe occurs. 
From this maximum the curve falls to the composition of the 
compound T1,S., after which there is another horizontal tract 
at 195°. Here again two liquid layers occur, the upper being 


a solution of a selenide in selenium, and the lower being the 
selenide Tl,Se;. 


! | 
' eis Ui tne hy 
Sn etd Si, SF, pase, 






. 

















fm eee 





~~ 
8 
ts 
IS) 
G 
8 
CS 
iS) 
Q 
~) 
Q 
8 
N 
Q 
& 
Q 
S 
S 
aT Se 
SS 
Ss 
X 


Fie. 183. 


Selenvum-tin.—The selenides SnSe, Sn, Se; and SnSe, are 
known ; they were found by Biltz and Mecklenburg ! in a 
study of the equilibrium between these elements. The 
compound SnSe shows a maximum at about 40 per cent. of 
selenium and 861° (Fig. 183). The second compound occurs 
at 50 per cent. and 645°, and the third, not well authenticated, 
at the same temperature and about 57 per cent. of selenium. 
The curve falls to the left from the maximum at first quickly, 


1 Zeit. anorg. Chem., 64, 232 (1909). 


300 CHEMICAL COMBINATION AMONG METALS. 


then slowly, and finally almost vertically to the eutectic, 
which practically comcides with the melting point of pure 
tin. On the other side of the maximum the curve, after 
falling steeply, shows a discontinuity corresponding to the 
second compound. A more or less horizontal tract then 
suggests the occurrence of a lack in miscibility. 

The eutectic, which crystallises at 217°, is almost pure 
selenium. , 













































































1100 Ph Se 
1000 ees ee See ee. 
ol ALTA AAAN 
“LESAN 
goo BSS884 A A : NN 
es SSSS8Z7Z MAS 
600 == | 
“SSRs | 
4oOo See ' 
See ie ! 
Soo 
eat 10 yA ie nese) LO so 60 ran 90 Ga TEP 
Poe 1; mu Afonsr ae : 
Fia. 184. 


Selenvum-lead.—The system lead-lead selenide has been 
studied by Friedrich and Leroux! and by Pélabon.? The 
melting point of the selenide is very high. According to 
Friedrich and Leroux it is at 1088°, according to Pélabon 
at 1065°. Froma concentration of 50 per cent., at which the 
compound is formed, the curve falls continuously to the 
melting point of pure lead (Fig. 184). Corresponding with 
the melting point of lead (326°), arrests are noted for all 
mixtures from 0 to 50 per cent. 


1 Metall., 5, 355 (1908). 
2 (. R., 144, 1159 (1897). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 301 


Pélabon has investigated the further course of the curve 
in the region between the selenide and pure selenium. The 
curve falls to 70 per cent. of selenium, and remains level at 
673°, indicating the formation of two strata, the upper of 
which contains free selenium and the lower the compound. 
The existence of a compound PbSe, is not indicated. 

Selenium-antvmony. Selenium forms with antimony the 
compound Sb,Se, reported by Pélabon,! by Chrétien,? who 


650 | 


600 4/ / 


# 























Fig. 185: 


mentioned in addition the compounds SbSe, Sb,Se, and 
Sb,Se;, and also by Parravano,? who studied the system 
thermally. The compound (see Fig. 185) separates at 50 
per cent. and 630°. It does not mix with antimony in all 
proportions in the liquid state; two liquid strata occur with 
11 and 35 per cent. of selenium respectively. Between 60 
and 70 per cent. of selenium a change in direction of the 
curve indicates, according to Parravano, a lack of miscibility 
in the liquid state with an upper or lower critical point. 
1 J. Ch. Phys., 2, 437 (1904) ; C. R., 142, 207 (1906). 


2 O. R., 142, 1339 (1906). 
8 Gazz. Chim. Ital., 48, I., 210 (1913). 


302 CHEMICAL COMBINATION AMONG METALS. 


From 50 to 100 per cent. of selentum marked supercooling is 
observed. 

Selenvum-bismuth.—Selenium forms two compounds with 
bismuth, BiSe and Bi,Ses, observed by the thermal method 
through the work of Parravano.t The curve (Fig. 186) rises 
rapidly from the melting point of bismuth up to about 27 per 
cent. of selenium, where, between 600° and 610°, thermal 
effects are observed due to the formation of the compound 


? 

- 
a 
> 


ia] 
aN 



































Fig. 186. 


BiSe; this is confirmed by microscopical evidence. ‘The 
curve again rises to 706° and 37 per cent. of selentum and 
shows a maximum for the compound Bi,se. It then 
descends to about 625°, remains horizontal along a_ tract 
and subsequently falls almost vertically to the melting point 
of pure selenium. The compound Bi,Se, is not completely 
miscible with selenium ; for some mixtures, two liquid layers 
occur in the liquid state, the lower of which consists mainly 
of the compound and the upper mainly of selenium. 
Seleniwm-chromiaum.—Moissan (1880) obtained the com- 
1 Gazz. Chim. Ital., 48, I., 210 (1913). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 8038 


pounds Cr,Se, and CrSe by heating chromium chloride in an 
atmosphere of hydrogen selenide. The existence of these 
compounds is, however, not well authenticated. 

Selenvum-manganese.—Fonces-Diacon (1900) obtained the 
compound Mnse, which, he states, does not decompose on 
heating. 

Selenvum-iron.—Fonces-Diacon also prepared the follow- 
ing selenides of iron: Fe,Se3, Fe,5e,, or FesSe, and FeSe,. 
These on heating are changed into a compound whose com- 
position approximates to the formula FeSe. The homo- 
geneity of this product has not been clearly demonstrated. 

Selenvum-mckel and Selenvum-Cobalt. — According to 
Fonces-Diacon (1900) selenium forms with nickel and cobalt 
compounds with the following formule: M,Se, MSe, M,Se,, 
M,Se, and MSe,, where M = Co or Ni. His researches, 
however, were not founded on the most trustworthy methods. 

Selenvum-palladium.—Réssler (1895) isolated a selenide, 
PdSe. An alloy with 6 per cent. of selenium, on treatment 
with nitric acid, gave a compound with the formula Pd,Se. 

Selenvum-platinum.—Réssler also obtained a selenide with 
the formula PtSe, while Minozzi claimed to have obtained 
the compounds PtSe, and PtSe,, the first by precipitating a 
solution of the double cyanide of platinum and selenium 
with formaldehyde, and the second by reduction of the first. 


COMPOUNDS oF TELLURIUM (TELLURIDES). 


Tellurvum-copper.—Iwo compounds are formed, namely, 
Cu,le and Cu,Te,. The system has been investigated by 
Chikashigé !; the diagram is given in Fig. 187. The first 
compound is formed at 855° at a concentration of about 
66-6 per cent. of copper. It separates secondarily in the form 
of a series of mixed crystals with tellurium from melts con- 
taining 100 to 66 per cent. of copper, and primarily from 
melts with 66 to 50 per cent. of copper. At 623° the last 


1 Zeit. anorg. Chem., 54, 50 (1907). 


3804 CHEMICAL COMBINATION AMONG METALS. 


species of crystal reacts with the melt of composition D, 
forming the compound Cu,Te;. At 365° there is a thermal 
effect, Cu,l’e; beimg transformed into another crystalline 
species. Since the maximal arrest occurs at the composition 
of the compound Cu,Te; it would appear that this is a poly- 
morphic transformation of the compound. 
Tellurium-silver—The compounds Ag,Te and AgTe are 
known. Pushin? has investigated the system and also 





4100 


TIN Tai 
FINI TIT 


LLL 


LALLA 











Cad 











$00 
Joo ~ Coe, Te, 


2 GN 


500 


ott | NZ 


LALA 










































































er 10 10 30 40. 450 6O =o go huh em ede 
—> /, ne ovloasaes te 
Fig. 187, 


measured the electrolytic potential of the alloys of these 
slements. The system has also been studied by Pellint and 
Quercigh.? Their diagram is shown in Fig. 188. Ag,Te gives 
a maximum at 959° and 33°3 per cent. of tellurium. Between 
this and pure silver an eutectic point is found at 872°. For 
higher contents of tellurium, 7.e., at about 50 per cent., 
thermal effects are observed at 444° and at 412°, due probably 
to the compound AgTe. The effect at 412° would appear to 
be due to a polymorphic transformation of this compound. 


1 Zeit. anorg. Chem., 56, 8 (1908). 
2 fh. Acc. Lincet, 19, I., 415 (1910) ; Gazz. Chim. Ital., 45, I., 469 (1915). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 305 


Tellurvum-gold.—The system has been investigated by 
Pélabon ? and by Pellini and Quercigh.2, The compound 










































































1000 Ka, -- 
GDN <j N 
4 VAX | 
«O00 / 
10 : Adle 
ie 
600 HIN 
foa VL N/ 
VIALE, i 
2 | Lae 
300 == 
eo fo fe] $0 40 60 go 100 
i w Mm ows & 
Fia. 188 







































































if 7. 
LLYLALLNLLY [Lc pret | 
eos O to) 40 o sO 60 zo go go 100 

—_—__> a mam OF OnE 1 Te 


Fig. 189. 
AuTe, occurs, and gives a maximum on the diagram (Fig. 189) 
at 460° and 66-6 per cent. of tellurium ; on both sides of the 


1 (, R., 148, 1176 (1909). 
2 R. Acc. Lincet, 19, IL. 445 (1910). 


306 CHEMICAL COMBINATION AMONG METALS. 


maximum, eutectics are found, the one with gold at 53 per 
cent. of tellurium and 450°, and the other with tellurium at 
88 per cent. of tellurium and 416°. Solid solutions are 
formed to a limited extent. 

Tellurvum-zinc.—Tellurium forms with zine the com- 
pound ZnTe, observed by Kobayaski + by means of thermal 
analysis. It is indicated in the diagram (Fig. 190) by a 





1300 


4100 aad 
> BRAWN 
NN 

\ 








he $a 
S 
SS 
a 





AEA 
NN 


"LENS 


809 











, 


a 
A 


CEOLACL VIN 


Z 
CAGee 
SONS 

SS 

Sl 

~~ 


a Le 
SAS 
SN 
SS 





SAN 
SS 





LL 
La 
< 
RAs 
NNSEZ 


















































o 10 Lo 30 40 fo 6 #9 gu ] 400 
———_ i ua te ewer € 
Fie. 190. 


maximum at 1238-5°. Complete miscibility exists between 
the components in the liquid state. The compound TeZn 
is completely miscible with excess of tellurium in the liquid 
state, and from these liquid mixtures the compound sepa- 
rates primarily and tellurium secondarily. From liquid 
mixtures containing excess of zinc, the separation is chiefly 
of the metal. 

Tellurvum-cadmum.—The compound CdTe has _ been 
recognised. This system has been investigated by Kobay- 

1 Int. Z, Metall, 2, 65 (1911). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 307 


aski.t ‘The curve constructed by him (Fig. 191) consists 
of a single branch, for the eutectics practically coincide with 
the melting points of the pure components. ‘The compound, 
in spite of all efforts, could not be obtained in the pure state, 
nor was it possible to determine with exactitude the tem- 
perature and concentration of the maximum. Separation 
of the compound probably takes place from 50 to 55 per cent. 
of tellurium and at about 1040°. The cadmium partly 


TLOD! ve - 1100 


1000 > - L000 


J00 4K + 900 
800 4! + 800 
200 - 


G00 - 














4D 
400 - YUo 
300 = - 300 
200 - + 200 
Ca T = aI T T Te 


T i T ‘ A T ‘3 
O:: f0" — 20 GO: AO SOs. 00 FO GO. Ge 00 
Fiq@. 191. 


volatilises. The alloys from 1 to 2 per cent. of tellurium up 
to the composition of the compound could not be studied 
thermally because the components combined with such a 
creat evolution of heat. 

Cadmium in the liquid state only dissolves the compound 
to a small extent, so that a little above 700° a homogeneous 
melt is only obtained with 0 to 1-2 per cent. of tellurium. 

Telluriwm-mercury.—According to Pellini,? tellurium forms 


1 Zeit. anorg. Chem., 69, 4 (1911). 
2 Gazz. Chim. Ital., 40, 46 (1910). 


308 CHEMICAL COMBINATION AMONG METALS. 


the compound HeTe with mercury. This corresponds to the 
maximum shown on the diagram (Fig. 192) at 50 per cent. of 
tellurium and about 610°. The compound forms on the one 
side an eutectic with tellurium, while on the other it gives a 
continuous fusion curve down to the melting point of 
mercury, which means that the eutectic is practically 
coincident with this poimt. It is not known certainly 
whether solid solutions occur. 
Tellurvum-indium.—According to the investigations of 

































































E Hg ve 
: ES) ine 

et Be 

$oo ASS 

Loo ASS 

Se Sen Ba OS 
ee er ae ae 

EIG.-192: 


Koelsch (1910), these elements when fused together react 
with evolution of heat. From the analysis of a residue 
separated out on heating the mixture above 1000° the 
existence of a compound InTe appears probable. 
Tellurium-thalliwm.—These elements form the compounds 
Tl,Te, and TITe. The system has been studied by Chika- 
shigé,' and the diagram is shown in Fig. 193. The first com- 
pound gives a maximum on the cooling curve at 428° between 
27 and 80 per cent. of tellurium ; the second compound is 
formed at about 305° and 40-5 per cent. of tellurium. At 


1 Zeit. anorg. Chem., 78, 68 (1912). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 309 


200° it forms an eutectic X with tellurium, whose composi- 
tion 1s 67-6 per cent. of the compound TeTl and 82:4 per cent. 
of free tellurium. The eutectic horizontal extends from the 
ordinate marking the compound TeT! as far as the tellurium 
axis. ‘Te, Tl, dissolves in thallium, forming a series of mixed 
crystals. The saturated mixed crystal contains 24 per cent. 
of tellurium. From 100 to 76 per cent. of tellurium two 
liquid strata are observed which consist of the fuged saturated 
mixed crystal and fused thallium respectively. 





foo 





Soo 








Te. TI 
Cel aw 5 : “MN 
too [BX SY LF. TeTt 
Lo ba ° 7 
i 


= | SAN 
at ath i s. INN 
aR 7 \\\\ 



























































~ 

° 

cS 
Hm em oe a = 
a 
pee ee ae mee me 





vee ke 
| 
ADO" ieee ! 
(e) 10 20 30 4o 50 go yo ize) 30 100 
Fig. 193. 


TeTl does not form mixed crystals either with the com- 
pound or tellurium. 

Telluriwm-tin.—The compound SnTe has been recognised. 
The system has been studied by Fay (1907), Biltz and 
Mecklenburg 4 and Kobayaski.2 In the diagram (Fig. 194), 
the compound is indicated by a maximum at 52 per cent. of 
tellurium and about 800°. From this the curve falls at first 
steeply, then gradually and again steeply to the eutectic 
point, which coincides with the melting point of pure tin. 
Here, as in the case of Sn-S and Sn-Se, two layers occur due 
to differences in specific gravity and freezing point. On the 


1 Zeit. anorg. Chem., 64, 233 (1906). 
* Tbid., 69, 8 (1911). 


310 CHEMICAL COMBINATION AMONG METALS. 


other side of the maximum the curve descends rapidly to 
404° at 85 per cent. of tellurium, where an eutectic point is 
found. 

Tellurvum-lead.—These elements form the compound 
PbTe. The system has been studied by Fay and Gillson.! 
By addition of tellurium to lead the curve (Fig. 195) rises 
rapidly to the maximum at 915° which corresponds to the 
composition of the compound. It then descends to the 









9007 900 
Me AY: 
&00 pu o BUC. 800 
- Fay 
x KobayasWe. 








- 500 





+- 400 














300 4 : ee | 300 
200 - | | | eee + 200 
100 Be : L 100 
aS IL : : 1 ’ 1 n t 1 t 1 Te 
0 10 20 30 %0 50 60 70 80 90 100 


Fie, 194. 


eutectic between the compound and tellurium, which is at 
400° and 85 per cent. of tellurium. At 322°, on the lead side 
of the maximum, thermal effects are observed due to second- 
ary crystallisation of pure lead. No eutectic occurs here, 
or at any rate the eutectic is practically pure lead. 
Tellurium-arsenic.—These elements form a compound 
As Tes. The system was studied by Pélabon,* who reports 
a maximum at 362° and 40 per cent. of arsenic. The data 
obtained are, however, incomplete and not very reliable. 


' Trans. Am. Inst. Min. Eng., Nov. 1901. 
2 CO. R., 187, 648 ; 146, 1398 (1908). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 311 


Tellurvwm-antuemony.—The compound Sb,Tes is known. 
Studies of the system have been made by Fay and Ashley 1 


1000 




















































































































Phe 
Joo = 
“+ ay 
yoo RSSN7N 
x SSS GOs 
HSS 
ASSESS 
| CaS 
aa 70 20 30 40 $0 60 ¥O go 90 100 
Ea oe Sg er tao 
Fie. 195 
#00 
a SoyTe , 
boo Fora t 
7} | \! , 
TTT yf 
foo \ 
400 
ee 10. “80: Sor he. FOL bo" 620 fo = 9a.s«d1':00 





—_——_——» ae ae AA eiee Ce. 





Fie. 196. 


and by Pélabon.2 The diagram (Fig. 196) shows a maximum 
at 629° and 60 per cent. corresponding to the compounds, 


1 Amer. Chem. Journ., 27, 95 (1902). 
2 Ann. Chim. Phys., (8), 17, 539 (1909). 


312 CHEMICAL COMBINATION AMONG METALS. 


Solid solutions are formed between the compound and 
antimony. ‘The curve then descends to 427° and 86 per 
cent. of tellurtum, which is an eutectic point. Between 
tellurium and antimony an extensive range of solid solutions 
occur. Haken (1910) has carried out measurements of 
electrolytic potential on these alloys as well as‘ on those of 
bismuth and tellurium. His data confirm the existence of 
the compound Sb,Te,. 

Telluriwm-bismuth.—The telluride Bi,Te, is known. The 


| 

















bo 9 Beqte, 
ZZ: 
Le 


YUM 


TLD LF LLB 2 ABS 








MW, yy 
Wd. 





t00 












































Fia. 197. 


system bismuth-tellurium has been investigated by Monke- 
meyer + and by Pélabon.2. The diagram constructed by 
the former is shown in Fig. 197. It is quite simple, showing 
a maximum at 573° and 60 per cent. of tellurium, correspond- 
ing to the compound and two eutectic points, one at 2 per 
cent and 261°, and the other at 93 per cent. and 887° The 
existence of solid solutions has not been established ; the 
eutectics being so near to the pure components, they could 
only have a very limited range. 

Haken (1910) made measurements of the electrolytic 
potential and electrical conductivity of these alloys. 


1 Zeit. anory. Chem., 46, 419 (1905). 
2 CO. R., 187, 648 (1903) ; 146, 1397 (1908) ; Ann. Chim. et Phys., (8), 17, 526 (1909). 


HETEROPOLAR INTERMETALLIC COMPOUNDS. 313 


Recently G. C. Trabacchi? studied the Hall effect in these 
alloys and obtained curves similar to those of Haken. 

Tellurium-vron.—Fabre in 1887 obtained the compound 
TeFe by direct combination of the elements. Its existence 
is, however, not well established. 

Tel’urvum-cobalt and tellwrvwm-nickel.—Tellurides of the 
general formula MTe (M = Co or N1) were obtained by Fabre 
in 1887, and in 1879 by Margottet. Tibbals (1909) obtained 
the compound M,Te, 4 H,O, which on heating was changed 
by loss of tellur-um and water into MTe. 

Tellurvum-platinum.—The compounds of tellurrum and 
platinum were prepared synthetically by Réssler (1897), who 
reported the following: PtTe,, PtTe and Pt,Te. The 
existence of the last two is, however, doubtful. 


1 Nuovo Cimento, (6), 9, 3 (1915). 


CHAPTER VII. 


TERNARY INTERMETALLIC COMPOUNDS. 
General Remarks. 


THE application of thermal methods to the study of inter- 
metallic equilibria has given unlooked-for results, even in 
systems of more than two components. Up to the present, 
however, very few ternary intermetallic compounds are 
known, and even in these cases, the theoretical discussion of 
their equilibrium diagrams is far from complete. We shall 
confine ourselves to a brief treatment of this section of our 
subject, and, although we are here interested mainly in inter- 
metallic compounds, it will be necessary to describe some 
types in which compounds do not occur. The ternary 
equilibria are rather obscure from a thermal point of view, 
and additional complications are introduced by the difficulty 
of graphic representation, which in such cases often requires 
a knowledge of the principles of higher geometry. 

In the study of a system of three components, A, B and C, 
it is first of all necessary to understand the three binary 
systems 4B, BC and AC. These being known, the curves 
belonging to the ternary system are to some extent shadowed 
forth. | 

J. W. Gibbs,! G. C. Stokes,? and Roozeboom ® have pro- 
posed methods for the graphic representation of three com- 
ponent systems ; we shall describe that of Gibbs, which in 
this kind of work has come into ordinary use. Gibbs 
represents all the states of equilibrium which can occur in a 
ternary system by means of an equilateral triangle in which 

1 Trans. Com. Acad., 3, 176 (1876). 


2 Proc. Roy. Soc., 49, 174 (1891). 
3 Zeit. phys. Chem., 15, 147 (1894). 


TERNARY INTERMETALLIC COMPOUNDS. 315 


the vertices represent the three components 4A, B and C. 
Any point inside the triangle represents a mixture of all 
three components whose sum is equal to unity, while a point 
in one of the sides of the triangle represents a binary mixture. 
Dividing the sides into tenths, we can show the variation in 
composition of binary mixtures. Similarly, by dividing 
perpendiculars dropped from the vertices into tenths and 
drawing a series of lines parallel to the sides, we can define 
the composition of all possible ternary mixtures. For 




















WAT 
WANA VA, 


Fig. 198. 


example, the point P in Fig. 198 represents a ternary mixture 
containing -2 of component A, -7 of component B, and -1 of 
component C,, or 20 per cent. of A, 70 per cent. of B and 10 
per cent. of C, if 100 be substituted for unity. 

If perpendiculars be dropped from any point within an 
equilateral triangle to the three sides the sum of the lengths 
of these perpendiculars is equal to the length of a perpendicu- 
lar from one of the vertices to the opposite side, so that by 
adopting a suitable scale the composition represented by any 
point can quickly be found. 

As in the case of the binary systems, we shall again reduce 
the numerous equilibria for three component systems to a 


316 CHEMICAL COMBINATION AMONG METALS. 


few fundamental types. We may arrange them in three 
classes :— | 

Cuass I.—The three components crystallise in the pure state 
without formation of mixed crystals or chemical compounds. 

Cuass I].—The three components form mized crystals but do 
not combine chemically. 

Cuass IIIl.—The three components combine chemically to 
form either binary or ternary compounds. 

CuAss I.—The phenomena of crystallisation in ternary 


B ¢ 








Fie. 199. 


systems where the components separate in the pure state 
have been carefully studied and are well recognised. Using 
Gibbs’ triangular system of representation described above, 
the most simple case which can be presented is shown in 
Fig. 199. The diagram is divided into regions I., IT. and III. 

As was said above, along the sides of the triangle the binary 
systems which compose the ternary system are indicated ; 
from these sides the three lines ae, be and ce start and meet in 
the point e, which is the ternary eutectic. The points a, b 
and c represent the three binary eutectics BC, C A and A B 

1 A system which has been very carefully studied is that of lead-tin-bismuth, 


described by G. Charpy, C. R., 126, 1569 (1898), and Bull. Soc. d@ Lncour., (5), 3, 670 
(1898). 


TERNARY INTERMETALLIC COMPOUNDS. 317 


respectively. Just as the melting point of a substance is 
lowered by addition of another substance, so in the case of a 
binary eutectic the addition of a third substance lowers the 
melting point until the ternary eutectic is reached which has 
the lowest melting poimt of all possible ternary mixtures. 
At the ternary eutectic point we have the co-existence of 
three solid phases, one liquid phase and a vapour phase, so 
that according to the phase rule the system is invariant, or, in 


A 














rr 





B 
Fig. 200. 


other words, all the conditions of this equilibrium are deter- 
mined. 

The nature of the ternary eutectic will be more clearly 
understood by using a triangular prism instead of an 
equilateral triangle for the purpose of graphic representation. 
By this means temperature can be represented as well as 
composition. In Fig. 200, the binary systems 4 B, BC and 
CA have their eutectics in a, b, and ¢ respectively. The 
fusion curves for these systems are, of course, da B, BbC 
and Cc A respectively, each lying in a plane formed by one 


318 CHEMICAL COMBINATION AMONG METALS. 


of the prismatic faces. The curves a e, b e and ¢ e, which 
show how the eutectic point of a binary system is lowered by 
addition of a third component, are called the ternary eutectic 
curves. Three plane surfaces meet in the ternary eutectic 
point ; they represent the bivariant equilibria of one com- 
ponent and a liquid phase. The ternary eutectic curves 
represent monovariant equilibria, while the ternary eutectic 
point, as was said above, represents a non-variant system. 

A section parallel to the base of the prism will, of course, 
give an isotherm of the system. 

Cuass I].—The equilibria of ternary systems in which 
solid solutions occur are exceedingly complicated, and their 
discussion would carry us beyond the limits imposed on 
this work. The problem is of great interest, although, since 
the existence of ternary compounds has only been observed 
in a few cases, it has not a direct bearing on our subject. 
The problem is often rendered more complex by the occur- 
rence of gaps in the isomorphism of the components. 
Systems in which ternary mixtures exhibit complete iso- 
morphism have been studied by Schreinemakers,! Janecke,? 
and Parravano and Sirovitch.2 When one considers the 
numerous cases which can exist in binary systems in which 
isomorphous mixtures are present, the complicated nature 
of ternary systems with occurrence of isomorphous mixtures 
is only to be expected. 

Cuass III.—In this class of ternary equilibria we meet 
complications. We shall discuss a few possible cases which 
will arise according as one or two binary compounds appear 
or as a ternary compound is formed. ‘The last case is the 
most: interesting for our subject as it enables us to throw 
some light on the formation of ternary compounds. 

Type [.—Of the three components, completely miscrble vn the 
liquid state, two, A and B, form a binary compound D. We 


1 Zeit. phys. Chem., 52, 513 (1905). 

* L[bid., 67, 641 (1909). 

3 Gazz. Chim. Ital., 41, I., 417, 478, 569, 621 (1911); 42, I. 417 (1912). Also 
N. Parravany, ibid., I., 220 (1913). 


TERNARY INTERMETALLIC COMPOUNDS. 319 


shall assume for the sake of simplicity that no solid solutions 
occur and that the binary compound melts without decom- 
position. Figs. 201 and 202 indicate the character of the 
diagram, using the method of graphic representation 
explained above. In both diagrams the points K, and K, 
respectively are the two ternary eutectic points ; we have in 
equilibrium the solid phases A, B and D, together with a 
liquid phase at the one point and the solid phases B, C and D 
and a liquid phase at the other pomt. The crystallisation 























é 


Hig. 201, Fi@. 202. 


in such liquid mixtures occurs as in the binary mixtures of 
pure substances. 

Type Il.—Of the three components, completely miscible vn 
the liquid state, A and B form a compound D, and A and C 
form a compound E. 

As in the preceding case, we shall exclude the formation of 
mixed crystals. The equilibrium diagram is shown in 
Fig. 208. After what has been said with regard to the pre- 
ceding case, the crystallisation along the line D’ EH’ is worth 
notice. The crystallisation processes for the various mix- 


320 CHEMICAL COMBINATION AMONG METALS. 


tures of D and 7 can be compared to those occurring in a 
binary system of two components which form an eutectic, and 
which, though completely miscible in the liquid state, do not 
form mixed crystals. As we shall see in the description of 
the ternary system magnesium-aluminium-zine, this part of 
the diagram often serves to indicate whether or not a ternary 
compound occurs. 

Type II1.—The three components are completely miscible in 
the liquid state, A and B form a compound D, A and C form a 
compound Ii, and B and C form a compound F. 


A 








Fia@. 203. 


If solid solutions do not occur and the compounds melt 
without decomposition, the diagram can be represented by 
Fig. 204. Four ternary eutectics will occur, three of which 
will represent the equilibrium of two compounds and a pure 
component, while the fourth will represent the equilibrium 
of the three compounds. 

Typr 1V.—The three components form a ternary compound. 
Excluding the formation of mixed crystals and of binary 
compounds, and supposing that the components are com- 
pletely miscible in the liquid state, this type is represented 
by the diagram shown in Fig. 205. A number of eutectics 
occur. Three binary eutectics, a, b, and ¢, lie on the sides 


TERNARY INTERMETALLIC COMPOUNDS. 321 


of the triangle. There will also be three eutectics lying 
along the lines joining to the corners of the triangle 


A 
' 













2 
ro ee 
. Se vA 





Fig. 204, 


and three eutectics between these and the binary eutectics 
GD and c; 


A. 











2 oo 

FIG, 205, 
Sodium-potassvum-mercury. Sodvum-cadmium-mercury.— 
The study of these systems has been carried out by 
Jainecke,! but the results are not as yet decisive. In any case 


1 Zeit. phys. Chem., 57, 507 (1907). 
C.M. 21 


322 CHEMICAL COMBINATION AMONG METALS. 


Jainecke has been able to demonstrate the presence of a 
chemical compound in each of these systems. The com- 
pounds show the following characteristics: (1) a homo- 
geneous crystalline structure when viewed under the micro- 
scope; (2) a definite melting point; (8) all alloys having 
concentrations slightly different from that of the compound 
have a lower melting point. 

Jainecke’s curve shows that marked super-cooling takes 
place. The compound NakHg, crystallises in shining 
hexagonal prisms of a steel blue colour and is oxidised on 
exposure to air. Its melting point is 188°, while that of 
NaHg is 217° and that of KHg 178°. By addition of KHg 
the melting point of the ternary compound may be lowered 
about 18°, and by addition of NaHg about 5°; further 
addition of these substances leads to a rise in melting point. 
A lowering is, however, produced by sodium or potassium, or 
by amalgams containing more of these metals than the 
binary compounds mentioned. 

The compound NaCdHg which separates in crystals of the 
recular system melts at 325°, as compared with 350° for 
NaHg, and 880° for NaCd,. , Addition of the latter two 
compounds lowers the melting point of NaCdHg by about 
0", 

Magnesium-aluminvum-zinc. — The system has been 
studied by Eger.t The diagram was constructed by means. 
of a number of sections perpendicular to the fundamental 
concentration plane. ‘The first section is the line joining 
the points representing the compounds Al,Mg, and Zn,Mg 
on the diagram ; the diagram is thus divided into two parts 
—on the one hand the quadrilateral Al-Al,Me,-Zn,Mg-Zn 
and on the other the triangle Al,Me,-Me-Zn,Meg. - The 
melting point of each binary compound is lowered by addi- 
tion of the other, and an eutectic point occurs at 450° and 
15 per cent. Zn, 37-5 per cent. Al and 47-5 per cent. Mg. 
The extent of the eutectic horizontal indicates the occurrence 

1 Int. Z. f. Metall., 4, 50 (1918). | 


—— 
—_— ones 


a third phase exists with an obscured maximum. 


TERNARY INTERMETALLIC COMPOUNDS. 328 


of mixed crystals. At the eutectic point two kinds of 
mixed crystals are in equilibrium with the melt. A series 
of arrests at 505° show a maximum at 61 per cent. Zn, 
12-5 per cent. Al and 26-5 per cent. Me. 


In addition to the two components Zn,Mg and Al,M,¢e 























x 
‘N 
\ 
a Oo a 
oe 7 
Pe 
Ca 
wes 
NN 45 
x ra 
ae 
a \ es 
‘ ‘ 
2 
jek 2 AEN 
i 4 a \ 
i re ” . re 
fe ’ . 
i 13 3 “6 
NA * 
; ; x 
1 is De 
S j ‘ 
-ik-+- \ 
: : oN 
Not ‘ . 
Noa \ 
oe Ne = x 
—pa_y ee Sd estar abs aan . 
: ‘ : oe, eo , N 
: iw N 
f : ‘ a nf + > 
q . By HEN mee \ 
—-_+ ‘s Oe fiat ear eet ee XN 
foo H ‘ 4 ‘\ 
han Ja o o *. , 
oe & oe a eit 3 \ 
\ (ete as a in ied Wh 
’ bene ‘ tees 
ears . : NS 
’ pea ae 
~ . . ‘ . ‘ % A ee 
ee Pa iees xanga, J ee , 
y ee * = ‘ ‘ ‘ ‘ 3 = \ 
ha eee Jo . \ 
/ : : Be Fiera en : 3 
Ve ‘ ms ae : 
i) SyVe . 
a a ' 1 \ : 
Z| ! ee G 
i} 
1 1 
| { ; 
; \ ' 
{ \ 
' 
bee oor . 
wv i wr “ 
7 
oe es - 
a 
le = Ne 


Fig, 206, 


The com- 


pound of the formula ZngAl,Me, melts at 505° with 
decomposition. 
Zn,Al,Mg, 2 melt A + mixed crystals B. 


Melts of composition approaching that of MgZn, separate 
another series of crystals. 


21—2 


y,2 


324 CHEMICAL COMBINATION AMONG METALS. 


Micrographic study was not possible on account of the 
hardness and brittleness of the two binary compounds. The 
equilibrium diagram in the region Al,;Mg,-Zn,Mg-Zn-Al 
comprises a convex surface of primary solidification. Near 
to the point indicating pure zinc there are two eutectic 
points and a transformation point. 

In the region Mg-Al,Me,-Zn,Meg, the ternary compound 
does not form mixed crystals; the eutectic practically 
coincides with the peritectic point. 


BAe 








C Ay, Le - ALK aAgle Neg a eat Seren ee 
40 DOR VA 600 90 80 Io 
AAgle Alome Leff 
Fie. 207. 


Stilver-gold-tellurewm.— This system has recently been 
investigated by Pellini,t who has directed his researches in 
particular to the system Ag,T'e-AuTe,-Te and succeeded in 
defming the compound (AgAu),Te,, in which gold partly 
replaces silver. The experimental study of this system 
presented difficulty, for the thermal phenomena were not 
always well defined. The diagram is reproduced in Fig. 207. 
The ternary compound does not separate directly, but 
melts with decomposition. The points a, b, c, e on the 
diagram represent nonvariant equilibria. The investigation 
of all the states of equilibrium in this system is by no means 


1 Gazz. Chim. Ital., 45, I., 469 (1915). 


TERNARY INTERMETALLIC COMPOUNDS. 325 


complete, and the complications which occur in the binary 
systems comprised in it vastly increase the difficulties of 
thermal investigation. 

The possibility of the formation of ternary compounds of 
silver, gold and tellurium seems evident when it is considered 
that such compounds occur naturally. Gastaldi+ has 
recently described such a compound, to which he gives the 
formula (AgAu),T'e;. 

These ternary combinations of course belong to the group 
of heteropolar compounds. If they result from the union 
of dissimilar atoms, the partial substitution of an electro- 
positive element by another closely related element is 
always possible. No other ternary combinations have as 
yet been deduced from the study of equilibrium diagrams. 
From the physico-chemical point of view these compounds 
are only known to a very small degree owing to the lack of 
systematic researches, as 1s oe case in so many binary 
combinations. 


1 Rend. Acc. Sct. Fis. e Nat. di Napoli (3), 17, 22 (1911). 


326 


TABLES. 


Meutina Points AND Atomic WEIGHTS OF THE MORE > 











IMPORTANT METALS AND METALLOIDS. 
Atomi Melting point. 

Element. Symbol. me Dee 0. 
Aluminium Al 27°1 658°7 
Antimony Sb 120-2 630°5 
Arsenic . _ As 750 850 (7) 
Barium . Ba 137°4 850°0 
Beryllium Be 9°1 1278:0 
Bismuth Bi 208°0 PZ Ac0 
Boron B 11°0 2000—2500 (7) 
Cadmium Cd 11274 320°9 
Calcium Ca 40°1 800 ea. 
Carbon . C (diamond) 12-0 >" 3600 ca. 
Cerium . Ce 140°25 > 800 
Ceesium . Cs 132-9 26 
Cobalt Co 59°0 1480 
Chromium Cr 52°1 1520 
Copper . Cu 63°6 1084°1 
Gallium Ga 70:0 30 
Gold Au 197°2 1063°5 
Indium . In 115°0 155 
Iridium . Ir 193-0 2350 (7) 
Tron Fe 559 1530 
Lanthanum La 138°9 810 (2) 
Lead. Pb 206'9 327°4 
Lithium. Li 7°03 186 
Magnesium Mg 24°36 635 
Manganese Mn 55°0 1260 
Mercury. ; Hg 200°0 Soe) 
Molybdenum . Mo 96°0 2500 (7) 
Nickel Ni 58°7 1451 
Osmium. Os 191-0 2700 (7) 
Palladium Pd 106°5 1549 
Phosphorus Pe 31:0 I, 44—IT. 930 
Platinum Pt 194°8 1780 
Potassium K 39°15 62°5 
Rubidium Rb 85'5 38 
Ruthenium Ru 101°7 2450 (7) 
Selenium Se 79°2 217 
Silicon Si 28°4. 1420 
Silver Ag 107°93 961°5 
Sodium . Na 23°5 97°5 
Sulphur . 326 | ee rrr ae 
Strontium Sr 87°6 > Ca, < Ba (7) 
Thallium Tl 204°1 302 
Tellurium Te 127°6 450 
Tin Sn 119°0 232 
Titanium Ti 48°1 1800 
Tungsten W 184:0 > 3000 
Uranium Ur 238°5 < 1850 
Vanadium V 51:2 1720 
Zine Zn 65°4 419 




















327 


TABLES. 


"O-ELT = wnt qi07} X “0.991 = wuniqi gy 
‘0-091 = wniqioy, ‘€: OCT ‘unueUeg ‘9.eF[ = wnIWApooN ‘Cc. QF] = wntwApooselg—: s}uswe[a SULMOTIOY eq} 9pnpoul qK—<aON , 










































































































































































¢.88 = 0 8-883 = UL. G66 = ty | Or 
806 = 1d | 6-908 = 4d | 1-403 = LL | 0-008 = 3H | 3-L61 = nV 6 
8-F61 = Id . : 
‘0-861 = I] 0-781 = | O-Tet = eg OEE FG-OF1) 6. gey = ert | F-Le1 = ea | 6-ZEI = 80 | 0-81 = 0X |8 
‘ — ¥94X a” 
0-161 = 80 
16-931 =I | 9-L21 = 9], | 2-021 = 48] 0-611 =ug |0-GTI = Ul | F-ZIT=Po |e6-L0l = SV re 
€.901 = Pd 
0-601 = 44 jog = OW | Lee = ON | 0:06 = 17 068 — & | 9-916 | oeg Sa" | 6 is—79 19 
L-LOT = 0Y 
96-6L=1¢ | zo.—=og | OSL=SV! ozL=0n| 0.0L =eH| F99—=UzZ] 9.e9 =n9 g 
0-68 = 09 
L. g¢ =IN| 0-9¢ =u] L-z¢ = 19 CiS=A “Pert ler = 98), 10S 8D) £168 = i Or clea ie EB 
‘6.99 = ag | | 
cP.cg = 19 | 90-28 =¢ Oe = F-8Z =19| 1-L6 =IvV | 98-¥e = FIN | 20. ‘€6 =BN | 0-03 = 9N | 
0-61 at OO =O -10-Fi—N 0-41 =) Gr I tease & L6G og:| SOsg. = fT ¥=0H'6G 
| 800-1 = H I 
rou AOR te Oar ‘O'U [Ou ‘O° Ow O°" u 
Ha | ‘HY ‘HY HY os = = = 
TITA TIA | TA “A “AI ae TI zi ‘0 g 
dnoiyy dno | dnoay dnory dno) dnory dno dno dno) 2° 
| 





“SEINHWATY AHL AO WALSAQ JNIdOTddd 


328 CHEMICAL COMBINATIONS AMONG METALS. 


BINARY SYSTEMS STUDIED THERMALLY. 


(Homopolar Combinations.) 





Na| K |Rb/ Cs Caf AgiAu| Bel CalMgl Za|Cd|Hg| Al| In| TI| SaPb|Ce| Sb{ Bi| Cr|Mo|Ma| Fe| Ni| Co 

















0} 0|—| ss OO ee cele eee ee 












































| 
CH-EH10/C-|l0/€[C|C/o|-Cic/¢|=|¢| || =| /— 
FIFIF =| |= 101 €| | C/0\=|¢] C/c\| ¢]¢ | ||| |= |— 
| ISIC = ||| |= |= 

S|=|-|=F FF |= 1C/= |= =F |= = 








0/0} C}C/C|C|Cj—|C|—|0|C|O|—|C| O/ O|—| 0] O/ 0/0 OO 

































































| |O|—|C| C{C/C|—| C|—| O/C} O|—|C] 0, O|— C/O] O/ OJ O/C 
i | I-l-[e} Cc] C|—|C|—| 0} €| €|-| C|O|—|—| C} 0] 0/0] O/O}, 
| Ui onstage Onna elec ole Clee 
Pelee ee eC eee lie sie 
Poa alee TOS ere te Oye CHC eerie Cla le | 

pole a eo OPO IO) O10 Cio Clee ley e|-i— 
le See ae ae Or OO Ol Chore el ee er 
Peco Pits leu lae ee Olle pO eevee etn oes 

Se Site i LOMO OC OTC ee CIC ak 

oats ee ee Js SO 8 eo ea ce Pa dl 
Pelistels leas ee eC Se OOO ac 


































































































mee | | [O|;C|CjJO,O|/—|CjC|C|Cj|—|C 

| | [C{O;O|Oj/—jO| O]OjO;C]|C 

C = Chemical combination. Wt A Feces raed! rl lars eed 

: teed Oreille lcrerererc 

O = Absence of chemical combi- Pee PO Ielorc io 
nation. 

— = No ae study made up to abe SSNs orien ee Ol ies 

the present. es oe ae oa WO I rae Coil 

[eee eile es OLO LO 

ele sel aok ae se iy Cla 

Plt delete eal le ROL le 

| ze | | eal Poles |= 

Pues a en eerie 





















































BINARY SYSTEMS. 329 


BINARY SYSTEMS IN WHICH CHEMICAL COMBINATIONS DO 

















NOT OCCUR. 

| System. Bibliography. 

Ag-As K. FRIEDRICH AND A. LERoux, Metall., 3, 194 (1906). 

Ag-Au | RoBERTS-AUSTEN AND KIRKE ROSE, Chem. News, 87, 2 (1904) ; 

| HrEYcOcCK AND NEVILLE, Phil. Trans., 189, A 69 (1897). 

'Ag-Bi | G. J. PETRENKO, Z. anorg. Ch., 50, 138 (1906). 

| Ag-Co 57 00, 2L5 (1907). 

|Ag-Cr | G. IlinpRIces, Z. anorg. Ch., 59, 425 (1908). 

|Ag-Cu | K. FRIEDRICH AND A. LEROUX, Metall., 2, 298 (1907); W. v 

| LEPKOVSKI, Z. anorg. Ch., 59, 290 (1908) ; HEYCcOCcK AND 

| NEVILLE, Phil. Trans., 189, A 25 (1897); N. KuRNAKOFF, 

| N. PusHIN AND ZUKOVSKI, Z. anorg. Ch., 68, 123 (1910). 

Ag-Mn | G. HinpRicus, Z. anorg. Ch., 59, 440 (1908). 

|Ag-Na | E. QUERCIGH, Z. anorg. Ch., 68, 303 (1910); C. H. MATHEWSoN, 
Int. Z. Meiall., 1, 57 (1911). 

Ag-Ni | G. J. PETRENKO, Z. anorg. Ch., 58, 213 (1907). 

Ag-Pb | K. Friepricu, Metall., 3, 398 (1906) ; PETRENKO, Z. anorg. Ch., 
58, 202 (1907) ; HEycock AND NEVILLE, Phil. Trans., 189, A 37 
(1897). 

Ag-Pd | R. Rurr, Z. anorg. Ch., 51, 316 (1906). 

Ag-Si | G. ARRIVAUT, Z. anorg. Ch., 60, 439 (1908). 

Ag-Tl | PETRENKO, Z. anorg. Ch., 50, 135 (1906). 

Al-Be | G. OESTERHELD, Z. anorg. Ch., 97, 6—40 (1916). 

Al-Bi | A. G. C. GwykrR, Z. anorg. Ch., 49, 318 (1906). 

Al-Cd ». 57, 150 (1908). 

Al-K 1B Pe ee SMrrir, Lia anorg. Ch., 56, 113 (1908). 

Al-Na | C. H. MATHEWSON, Z. anorg. Oh., 48, 193 (1906). 

Al-Pb | A. G. C. Gwrkr, Z. anorg. Ch., 57, 149 (1908). 

Al-Si W. FRAENKEL, Z. anorg. Ch., 58, 157 (1908). 

Al-Sn | A. G. C. GwYkrR, Z. anorg. Ch., 49, 315 (1906); Hrycock AND 
NEVILLE, Journ. Chem. Soe. 57, 376 (1890). 

AL Bod Md eres Na DOERINCKEL, Z. anorg. Ch., 48, 189 (1906). 

|Al-Zn | Heycock AND NEVILLE, Journ. Chem. Soc:, 71, 383" (1897); 

| SHEPHERD, Journ. of Phys. Chem., 9, 504 (1905). 

| 

|As-Au | K. Frrepricu, Metall., 5, 360 (1908). 

|As-Bi | K. FRIEDRICH AND P. LEROvx, Metall., 5, 148 (1908). 

As-Pb | K. Frrepricu, Metall., 3, 46 (1906). 

As-Zn | K. FRIEDRICH AND A. LEROUX, Metall., 3, 477 (1906). 

|Au-Bi | R. VoGEL, Z. anorg. Ch., 50, 147 (1906). 

|Au-Co | W. WAHL, Z. anorg. Ch., 66, 65 (1910). 

Au-Cu | N.S. KURNAKOFF AND ZEMCZUZNY, Z. anorg. Ch., 54, 164 (1907) ; 
ROBERTS AUSTEN, Proc. Roy. Soc., 67, 105 (1901). 

Au-Fe } E. ISAaK AND G. TAMMANN, Z. anorg. Ch., 58, 294 (1907). 

Au-Ni | M. LEvIN, Z. anorg. Ch., 45, 239 (1905). 

|Au-Pd | R. Rusr, Z. anorg. Ch., 51, 393 (1906). 

Au-Pt | Fr. DOERINCKEL, Z. anorg. Ch., 54, 347 (1907). 

|Au-Tl | M. Levin, Z. anorg. Ch., 45, 34 (1905). 





330 


BINARY SYSTEMS. 


BINARY SYSTEMS IN WHICH CHEMICAL COMBINATIONS DO 


NOT oOccUR—continued. 











| System. Bibliography. 

| 

‘Bi-Ca | L. Donskt, Z. anorg. Ch., 57, 215 (1908). 

|Bi-Cd | A. STOFFEL, Z. anorg. Ch., 53, 149 (1907). 

|Bi-Co | K. LEvKoNJA, Z. anorg. Ch., 59, 317 (1908). 

| Bi-Cr R. 8S. WituiaMs, Z. anorg. Ch., 55, 24 (1907). 

Bi-Cu | K, JERIomIn, Z. anorg. Ch., 55, 413 (1907); GAUTIER, Contr. a 

L étude des alliages, 1901, p. 110; Hrycock AND NEVILLE, Phil. 

| Trans., 189, A 25 (1897); Rowanp-GossErin, Bull. Soc. 

| @ Encour. (5), 1, 1810 (1896). . 

|Bi-Fe | E. Isaak AND G. TAMMANN, Z. anorg. Ch., 55, 60 (1907). 

Bi-Hg N. A. Pusuin, Z. anorg. Oh., 36, 214 (1903). 

|\Bi-Pb | A. STOFFEL, Z. anorg. Ch., 53, 150 (1907). 

\Bi-Sb | K. HUrrner anp G. TAMMANN, Z. anorg. Ch., 44, 138 (1905). 

| Bi-Si R. 8S. WiILuiAMs, Z. anorg. Ch., 55, 22 (1907). 

Bi-Sn | W. v. Lepkovski, Z. anorg. Ch., 59, 287 (1908); A. STUFFEL, 
ibid., 58, 148 (1907). 

|Bi-Zn | ARNEMANN, Metall., 7, 201 (1901); Hrycock anp NEVILLE, 

| Journ. Chem. Soc., 71, 394 (1897); SPRING AND ROMANOFF, 
Z. anorg. Ch., 13, 29 (1897). 

C-Ni K, FRIEDRICH AND P. LERoux, Metall., 7, 10 (1910). 

Hee? C. QUASEBART, Metall., 3, 28 (1906); L. StocKkEm, ibid., 3, 147 

| (1906). 

|\Ca-Sb | L. Donsx1, Z. anorg. Ch., 57, 217 (1908). 

|\Cd-Co | K. LEvKonjJa, Z. anorg. Ch., 59, 322 (1908). 

|Cd-Cr | G. Hinpricus, Z. anorg. Ch., 59, 427 (1908). 

|Cd-Fe | E. Isaak anp G. TAMMANN, Z. anorg. Ch., 55, 61 (1907). 

Cd-Hg | Bru, Z. phys. Ch., 41, 641 (1902). 

'Cd-Pb | A. StoFFEL, Z. anorg. Ch., 53, 152 (1907). 

Cd-Sn ” »” 29 53, 146 (1907). 

Cd-Tl | KURNAKOFF AND PUSHIN, Z. anorg. Ch., 30, 106 (1902). 

Cd-Zn | G. Hinpricus, Z. anorg. Ch., 55, 417 (1907); HEycock AND 
NEVILLE, Journ. Chem. Soc., 71, 383 (1897); GAUTIER, Bull. 
Soc. @ Encour. (5), 1, 1293 (1896). 

Co-Cu | R. SAHMEN, Z. anorg. Ch., 57, 3 (1908). 

Co-Ni | W. GUERTLER AND G. TAMMANN, Z. anorg. Ch., 42, 361 (1904). 

Co-Pb | K. LEvKonga, Z. anorg. Ch., 59, 314 (1908). 

Co-Tl is af : 09; 018 (1908). 

Cr-Cu | G. Hinpricus, Z. anorg. Ch., 59, 422 (1908). 

Cr-Pb a 5 », 59, 429 (1908). 

Cr-Sn ss ee ,» D9, 418 (1908). 

Cr-Zn ss ey » 59, 427 (1908); H. LE CHATELIER, 
Bull. Soc. d@ Encour. (4), 10, 388 (1895). 

Cu-Mn | R. SAuMEN, Z. anorg. Ch., 57, 23 (1908) ; ZeEMczuzNy, URASOFF 











AND RYKOVSKOFF, ibid., 57, 256 (1908). 


BINARY SYSTEMS. 3031 


BINARY SYSTEMS IN WHICH CHEMICAL COMBINATIONS DO 
NOT occuR—continued. 





System. Bibliography. 





Cu-Ni | GUERTLER AND TAMMANN, Z. anorg. Ch., 52, 27 (1907) ; KuRNa- 
KOFF AND ZEMCZUZNY, tbid., 54, 153 (1907); GauTIER, Bull. 
Soc. @ Encour. (5), 1, 13810 (1896). 

Cu-Pb | K. FRIEDRIcH AND A. LEROUX, Metall., 4, 300 (1907). 

Cu-Pd | R. Rusr, Z. anorg. Ch., 51, 225 (1906). 

Cu-Pt | Fr. DOERINCKEL, Z. anorg. Ch., 54, 337 (1907). 

Cu-Tl | R. SaAHMEN, Z. anorg. Ch., 57, 13 (1908). 


Fe-Mn | M. LEVIN AND G. TAMMANN, Z. anorg. Ch., 47, 141 (1905). 
Fe-Pb | E. Isaak AND G. TAMMANN, Z. anorg. Ch. 55, 59 (1907). 
Fe-Pt - . - - ,» 5D, 66 (1907). 
Fe-Tl ” ” 55, 61 (1907). 
Fe-V R. Vocer anv G. TAMMANN, Z. anorg. Ch., 58, 77 (1908). 
Fe-W | H.-Harxort, Metall., 4, 617, 673 (1907). 


Hg-Pb | N. A. Pusuin, Z. anorg. Ch., 36, 213 (1903) ; JANECKE, Z. phys. 
Ch., 60, 399 (1907). 

Hg-Sn | Van HETEREN, Z. anorg. Ch., 42, 129 (1904). Cf. p. 205. 

Hg-Zn | N. A. Pusuin, Z. anorg. Ch., 36, 214 (1903). 


In-Pb | N.S. Kurnakorr anv N. A. Pusu, Z. anorg. Ch., 52, 444 (1907). 
In-Tl 3 3 - ‘s 3 52, 445 (1907). 


K-Li | G. Masine anp G. TAMMANN, Z. anorg. Ch., 67, 189 (1910). 
K-Mg | D. P. Situ, Z. anorg. Ch., 56, 114 (1908). 


Li-Mg | G. Masine anp G. TAMMANN, Z. anorg. Ch. 67, 197 (1910). 
LiNa 3 - . py soy ONG LOO (LOTO), 


Mg-Na/| C. H. MAtuEewson, Z. anorg. Ch., 48, 194 (1906). 


Mn-Ni | ZEMczuZNY, URASOFF AND RykKoOvskOFF, Z. anorg. Ch., 57, 263 
(1908). 

Mn-Pb | R. S. WiLLiAMs, ibid., 55, 32 (1907). 

Mn-T] | N. Baar, ibid., 70, 360 (1911). 


Ni-Pb | G. Voss, Z. anorg. Ch., 57, 47 (1908). 
Ni-Tl of 3 9 O71, 50 (1908). 


Pb-Pt | Fr. DOERINCKEL, Z. anorg. Ch., 54, 361 (1907). 

Pb-Sb | W. GOUTERMANN, Z. anorg. Ch., 55, 421 (1907); Ro Lanp- 
GOssELIN, Bull. Soc. @ Encour. (5), 1, 1301 (1896). 

Pb-Si | S. Tamaru, Z. anorg. Ch., 61, 43 (1909). 

Pb-Sn | P. N. DEceEns, Z. anorg. Ch., 63, 212 (1909); A. STOFFEL, 
ibid., 58, 139 (1907); D. Mazzorro, Int. Z. Metall., 1, 289 
(1911). 

Pb-Zn | Heycock AND NEVILLE, Journ. Chem. Soc., 71, 304 (1897) ; 
SPRING AND ROMANOFF, Z. anorg. Ch., 18, 29 (1897); ARNE- 
MANN, Metall., 7, 201 (1910). 











3032 | BINARY SYSTEMS. 


BINARY SYSTEMS IN WHICH CHEMICAL COMBINATIONS DO 
NoT occuR—continued. 





System.| — Bibliography. 





S-Se W. E. RINGER, Z. anorg. Ch., 32, 202 (1902). 
S-Te M. CHIKASHIGE, Z. anorg. Ch., 72, 112 (1911). 


Se-Te | G. PELLINI AND G. Rio, R. Acc. Line., 15, 46 (1906). 
Sb-Si R. 8. WILLIAMS, Z. anorg. Ch., 55, 20 (1907). 
Sb-Sn ae yy Oo, 14.(1907);. REINDERS, tbed., 


25, 113 (1900). 


Si-Sn S. TAMARU, Z. anorg. Ch., 61, 42 (1909). 
Si-Tl . > », 61, 45 (1909). 


'Sn-Tl N.S. KURNAKOFF AND N. A. Pusuin, Journ. Chem. Soc., 30, 106 
| (1902). 

Sn-Zn | HEycocK AND NEVILLE, Journ. Chem. Soc., 71, 383 (1897) ; 
ARNEMANN, Metall., 7, 201 (1910). 








Tl-Zn | A. v. VEGESACK, Z. anorg. Ch., 52, 32 (1907). 











INDEX OF 


A 


ABEGG,.R:> 38,203. 
Ahrens, 251. 
Alexéjeff, 4. 

Amort, 278. 
Aristotle, 24. 
Armemann, 277, 330, 331, 332. 
Arrivaut, 168, 329. 
Ashley, 311. 

Aten, A. H. W.; 288. 
Auerbach, F., 89. 
Avogadro, 31, 32. 


B. 


Daan, N.. 113; 152; 161, 191, 198, 
249, 331. 

Bauer, 267, 286. 

Bachmetijeff, 154. 

Backer, 149. 

Baikoff, 158, 160. 

Barlow, 101, 233. 

Bartoli, 41. 

Barus, 67. 

Battelli, A., 154. 

Beek, 117, 119; 206. 

Becquerel, 81, 154, 164. 

Behrens, 99, 100. 

Bekier, 245. 

Belynsky, 226. 

Benedicks, C., 66, 90. 

Bengough, 275. 

Berry, 48. 

Berthelot, 164. 

Berthollet, 31, 34. 

Berzelius, 38. 

Bessler, 288. 

Biernacki, 204. 

Bill, 78, 000. 

Biltz, W., 121, 285, 286, 289, 299, 
309. 

Blough, 156. 

Blunt, 269. 

Bdttger, 112, 125, 164, 174, 206, 207. 

Boltzmann, 58. 

Bornemann, 105, 149, 296. 

Borodovsky, 291. 

Bottone, 90. 


AW EPRORS, 


Boudouard, 108, 109, 147, 160, 181. 
Bradley, M. W., 102: 

Brinell, 97. 

Bruni, G39; 163: 


C. 


CAILLETET, 207. 
Cambi, L., 80, 110, 112. 
Campbell, 155, 210, 269. 
Cannizzaro, 32. 
Carnot, 262. 
Carpenter, 149, 155. 
Carrara, G., 74. 
Carstanjen, 204, 278. 
Casamajor, 204. 
Cavazzi, 269. 
Chapman, 111. 
Charpy, 120, 316. 
Chavanne, 112. 
Chester, A., 175. 
Chikashigé, M., 21, 45, 220, 303, 308, 

332. 
Chrétien, 301. 
Chwolson, 66, 70, 85, 87. 
Clarke, 275. 
Clausius, 41. 
Coehn, 154, 164, 204. 
Cossa, 204. 
Croockewit, 164, 174. 
Curlt, 100. 
Curry, 155. 

Dy 


DALTON, 33, 51. 

Darmour, 208. 

Debye, P., 64. 

De Cegaris, 278. 

De-Chalmet, 257. 

Defacqz, 262, 270. 

Degens, 331. 

Délépine, 251. 

Descamps, 276. 

De Souza, 154, 164, 175. 

Dieckmann, 245, 279. 

Doerinckel, 117, 169, 230, 235, 262, 
329. 

Donski, 114, 115, 190, 191, 192, 193, 
194, 330. 


334 INDEX OF 


Ducelliez, 281. 
Duclaux, F., 64. 
Dumas, 164. 
Dumesnil, 278. 
Dupuis, 278. 


E. 


EDWARDS, 149, 155. 
Efremoff, 270. 

Eger, 194, 322. 
Einstein, 63. 
Emmerling, 268, 269. 
Empedocles, 24. 
Eucken, A., 85. 
Evans; 101, 


tO 


FABRE, 313. 

Faraday, M., 36, 70. 

Fay, 310, 311. 

Feodoroff, 163. 

Férée, J., 112, 125, 206, 207. 

Fetsch, 111. 

Fonces-Diacon, 298, 303. 

Fraenkel, 329. 

Friedrich, H., 71, 242, 275, 276, 277, 
278, 279, 280, 281, 282, 283, 286, 
290, 293, 295, 296, 297, 300, 329, 
330, 331. 

Fromm, 154. 

G. 

GALLACHER, 223. 

Gastaldi, G., 325. 

Gattermann, 258. 

Gautier, 120, 162, 163, 165, 168, 210, 
269, 330, 331. 

Gehlhoff, G., 85. 

Gercke, 271. 

Gibbs, W. J., 24, 74, 314. 

Giebelhausen, 252, 261. 

Giles,-W. B., 207. 

Gillson, 310. 

Gin, 255. 

Giolitti, 158. 

Giua, M., 12; 

Goldschmidt, 258. 

Gosselin, 194, 330, 331. 

Goutal, 262. 

Goutermann, 331. 

Gouy, 154, 164, 175. 

Granger, 268, 269, 275. 

Groth, 99, 100. 

Grotthus, 41. 

Grube, 108, 109, 181, 183, 184, 186, 
187. 

Guareschi, 31, 74. 


AUTHORS. 


Guertler, 66, 67, 122, 150, 159, 168, 
196, 256, 263, 265, 275, 296, 330. 

Guglielmini, D., 58. 

Guichard, 292. 

Guillaume, 87. 

Guillet, 87, 100, 155, 165, 210. 

Guldberg, 26, 32. 

Guntz, 125. 

Gwyer, 155, 210, 213, 216, 329. 


H. 

Haas, 150. 

Haber, F., 154. 

Hackspill, 222. 

Haken, W., 81, 83, 312. 

Hannesen, 252. 

Harkort, 331. 

Hautefeuille, 252, 255. 

Headden, 101. 

Fenty, 1231-75: 

Herschkovitch, M., 74, 78, 79, 149. 

Hertz, H., 89. 

Heteren, van, 205, 331. 

Heusler, 72. 

Heycock, 46, 100, 156, 162, 165, 167, 
168, 173,175, 176, 194, 329,330, 
Bo laoowe 

Heyn, E., 267, 286. 

Hildebrand, J. H., 204. 

Hill, 275. 

Hilpert, 245. 

Hindrichs, 168, 201, 210, 217, 329, 
330. 

Hiorns, 158, 275. 

Honigschmid, 251, 260, 262. 

Hoff, van’t, 42. 

Hogg, fir 

Hoitsema, C., 57. 

Holt, 261. 

Honda. Ky, 71: 

Hovsleff, 269. 

Howe, 151. 

Hiittner, 120, 330. 

Humphreys, W., 154, 204. 


1 
IGGENA, 125. 
Isaac, 202, 222, 226, 329, 330,331. 


de 
JACOBS, 258. 
Jaeger, 78. 
Jainecke, 139, 318, 321, 331. 
Jeriomin,. 330. 
Jolibois, 267, 269, 278. 
Joly, 254. 


INDEX OF 


Jones, HG .,5;.30, 
Jonker, 291. 

Joslin, 275. 

Joule, J., 154, 164, 208. 


Ke. 


KAHLBAUM, G. W. A., 48. 

Kaneko, 121. 

Kapp, 200, 233. 

Kasauzeff, 175. 

Kerp ii 2, 125: 

Kirke- Rose, 163, 164, 269, 329. 

Klein, 151. 

Knaffl, L., 175. 

Kobayaski, 306, 309. 

Koelsch, 288, 298, 308. 

Konovaloff, 204. 

Konstantinoff, 200, 237, 271, 273. 

Kremann, R., 12, 42. 

Kronchkoll, 204. 

Kupffer, 206. 

Kurnakott, N.S., 21,2425, 32, 33, 
OD; 31; 405 £1, 01, 52,66, SB, Ol, 
94, 97," 100; 105, 129; 13), 134; 
136, 139, 140, 145, 184, 186, 200, 
204, 218, 221, 237, 238, 329, 330, 
331, 332. 

Kusnetzoff, 129. 


ibe 
LAMB, 275. 
Laschtschenko, 236. 
Laurin, 288. 


Lautsch, 248. 

Lawrie, 176. 

Lebeau, 145, 257, 258, 262, 267. 

Le Chatelier, 25, 65, 66, 86, 87, 150, 
155, 272, 293. 

Leleux, 255. 

Lepkovski, 224, 329, 330. 

Leroux, A., 242, 255, 277, 283, 290, 
296; 297, 300; 329, oo0- O04, 

Levin, 226,329: 33, 

Levkonja, 121, 197, 202, 218, 226, 
238, 247, 264, 330. 

Levy, 260. 

Ley, 203. 

Liebenoff.. 65. 

Lineoln, 151. 

Lindemann, 63, 101. 

Littleton, F., 164. 

Losseff, K., 239. 


M 


MAEY, 53, 56, 125, 150, 164, 168, 
176, 178. 


AUTHORS. 335 


Manchot, 267. 

Mannheim, 206. 

Margottet, 298, 313. 

Maronneau, 269. 

Martin, 256. 

Martins, 269. 

Masing, 123, 125, 331. 

Mathews, 155, 210. 

Mathewson, 107, 127, 129, 131, 132, 
Pad. 136, 329,93) 

Matthiessen, 64, 86, 87, 150, 176, 206. 

Maxwell, 63. 

Mazzotto, D., 224, 233, 331. 

Mecklenburg, 289, 299, 309. 

Meerum-Terwogt, 120. 

Mendelejeff, D., 26, 34, 38. 

Merz, 154, 164, 175. 

Meyer, E. v., 24. 

Meyer, L., 34. 

Miller, 100, 169. 

Minozzi, 303. 

Miolati, A., 4. 

Moh, 88, 90, 93. 

Moissan, H.,.71,.112, 207, 208,251, 
204, 255,256, 258, 261, 262, 267, 
302. 

Monkmeyer, 194. 

Mourlot, 287. 

Muthmann, 117, 119, 206. 

Myers, 207. 

Mylius, 154. 


N. 
NAGAOKA, 71. 
Nasini, R., 25, 32. 
Nernst, W., 38, 49, 58, 63, 73, 75, 101. 
Neville, 46, 100, 162, 165, 167, 168, 
P73. 1:75, 176; 194, 329,-330.-33!, 
Bou: 
oF 


OESTERHELD, G., 145, 329. 
Ogg, 164. 

Ormandy, 204. 

Ostwald, W., 94. 


| ee 


PARKINSON, 269, 276. 

Parravano, 103, 120, 143, 149, 158, 
179, 195, 245, 278,301,302, 318. 

Partheil, 206, 278, 

Paschsky, 233. 

Paulovitch, P., 52, 204. 

Pélabon, 287, 288, 298, 300, 301, 
306, 310;-311, 312. 

Pellini, 102, 103, 297, 298, 304, 305, 
307, 324, 332. 

Perret, 179, 245. 


336 


Petrenko, 100, 162, 163; 165, 167, 
168, 329. 

Planck, 62. 

Plato, W., 47. 

Podkapajeff, 238. 

Pope, 101. 

Portevin, 246. 

Prelinger, ©.; 207. 

Proust; 25, 31, 34. 

Pushin, 36, 73, 80, 88, 105, 131, 140, 
15, 168,204,205; -218:-233, 236; 
304,329, 350;-351,832: 


Q: 
QUASEBART, 330. 
Quercigh, 102, 163, 304, 305, 329. 


Tk: 
RAMANN, 208. 
Rammelsberg, 100, 164, 175. 
Ramsay, 203, 204, 207, 278. 
Rausch, 36. 
Raydt, 196, 248. 
Rayleigh, Lord, 65. 
Regnault, 59, 154. 
Reinders, W.; 73; 75; 19; 223; oon: 
Renault, 204, 269. 
Richards, 204. 
Richarz, 72. 
Ringer, 292, 332. 
Rio, 298. 
nio.<Giy aoe: 
Roberts-Austen, 1, 148, 156, 329. 
Roche, 210. 
_ Rossler, 287, 296, 303, 313. 
Rolla, L218: 
Romano, 5,330,331. 
Roozeboom, Bakhuis, 14, 23, 205, 
256, 314. 
Rosenhain, 119. 
Rudolfi, E., 81, 82, 257. 
Ruer,- 121, 522) 233, 329. 
Ruez, 123. 
Ruff, 256. 
Rydberg, J. R., 88. 
Rykovskoff, 330, 331. 


S. 
Sackor, 151. 
Sahmen, 87, 147, 153, 330, 331. 
Saklatvalla, 271. 
Saldau, 173. 
Sander, W., 241. 
Schepeleff, 272. 
Schimpff, H., 59. 
Schneider, 296. 
Schoen, 279. 


INDEX OF 


AUTHORS. 


Schoénbein, 206. 

Schreinemakers, 318. 

Schroétter, 268, 269, 275. 

Schiibel, F., 59. 

Schiller, 129. 

Schirger, J., 112. 

Schiiz, 122. 

Schulze, F. A., 84. 

Schumann, 164, 204, 207, 208. 

Shepherd, 149, 156, 194, 329. 

Siebeck, 81. 

Sirovich, 318. 

Smirnoff, 88, 94. 

mith, 13h, 137; 138) 14142. 143; 
329.331, 

Speroni, G., 110, 112. 

Spring, W., 5, 330, 331. 

Stadeler, 255. 

Staigmiuller, 39. 

Stanfield, 156. 

Stead, 269. 

Stepanoff, 66, 184, 186. 

Stevanovitch, 101. 

Stockem, 330. 

Stoffel, 200, 224, 233, 330. 

Stokes, 314. 

Stortenbecker, 120. 

Suchein, A., 80. 

Svedelius, 87. 


5. 

TAFEL, 149. 

Tamaru, 331, 332. 

Tammann,. G.;'b; 7, 10,-13; 34,36, 
37, 46; 47, 707,37, 993,117; 120; 
PD. 1225123) 15. 196,21 99202, 
203, 206, 210, 222, 223, 226, 246, 
248, 258, 263, 265, 293, 329, 330, 
Sal. 

aratin.221: 

Tarugi, 204. 

Tavanti, 156. 

Thiel, 288, 298. 

Thompson, 169. 

Thomson, J. J., 72, 84. 

‘LID DAIS sOLoe 

Tissier, 204. 

Tivoli, 276. 

Trabacchi, 313. 

Traubenberg, 36. 

Treitschke, 200, 246, 293. 

Troost, 252, 255. 

Trouton, 49. 

Tukes, 119. 


U; 
Urasorr, 147, 170, 339, 331. 


INDEX OF AUTHORS. 


Ve 

VANSTONE, E., 129. 

Vegesack, v., 196, 332: 

Vigier, 269. 

Vigouroux, 257, 258, 262, 267. 

Vincent, 206. 

Viviani, 120, 158. 

Vocel. 100) (28.119. 170. bia to, 
P78, 179; 184,208; 231,283,209, 
329, 331. 

Voigt, W., 84. 

Vortmann, G., 206, 278. 

Voss, 188, 199, 202, 228, 246, 331. 


W. 
WAHL, 329. 
Wald, F., 24, 32. 
Wanklin.. 117, 
Wartenberg, v. H., 48, 49. 
Weber, C15, 81 bo, 
Wedekind, E., 72, 244, 260. 
Weith, 154, 164, 175, 244. 
Welsbach, Auer v., 233. 


337 


Werner, A., 34. 

Wibaut..J. Ps): 

Wiedemann, G., 84. 

Wilke-Doérfurt, L., 285, 286. 

Wilianis;: 200, 223; 994 Das. 955. 
330, 332. ; 

Wali Pee 5: 

Wilson, 204. 

Winkler, C., 206, 258. 

Winter, 125. 

Wohler, 258. 

Wologdine, 196, 272. 

Wright, 210. 

Wiinsche, H., 71. 


Le: 
ZAMBONI, 208. 
Zemezuzny, 66, 88, 160, 194, 221, 
226, 270, 272, 277, 329, 330, 331. 
Zettel, 262. 
Ziegler, 293. 
Zukowski, G., 35, 125, 145, 329. 


22 


oie ron 
oe 





INDEX 
Ag-Al, 165. Au-As, 276. 
Ag-As, 276. Au-Cd, 173. 
Ag-Ca, 161. Au-Hg, 174. 
Ag-Cd, 163. Au-Mg, 170. 
Ag-Hg, 164. Au-Mn, 179. 
Ag-Mg, 159. Au-Na, 106. 
Ag-Mn. 168. Au-P, 268. 
Ag-P, 268. Au-Pb, 177. 
Ag-Pt. 169. Au-S, 287. 
Ag-S, 287. Au-Sb, 179. 
Ag-Sb, 168. Au-Sn, 175. 
Ag-Se, 297. Au-Te, 305. 
Ag-Sn, 167. Au-Zn, 171. 
Ag-Te, 304. 
Ag-Zn, 162. B-C, 254. 
Al-Ag, 165. B-Fe, 252. 
Al-Au, 175. B-Ni, 252. 
Al-C, 254. Ba-Hg, 112. 
Al-Ca, 190. Ba-Si, 258. 
Al-Ce, 208. Be-Cu, 145. 
Al-Co, 213. Be-Fe, 180. 
Al-Cr, 217. Bi-Ca, 194. 
Al-Cu, 154. Bi-Ce, 231. 
Al-Hg, 203. Bi-K, 143. 
Al-La, 117. Bi-Mg, 187. 
Al-Mg, 181. Bi-Mn, 244. 
Al-Mn, 211. Bi-Na, 136. 
Al-Ni, 216. Bi-Ni, 246. 
Al-Sb, 210. Bi-P, 269. 
Al-Zn, 194. Bi-S, 287. 
As-Ag, 276. Bi-Se, 302. 
As-Au, 276. Bi-Te, 312. 
As-Cd, 277. Bi-Tl, 220. 
As-Co, 281. 
As-Cu, 275. C-Al, 254. 
As-Fe, 280. C-B, 254. 
As-Hg, 278. C-Cr, 255. 
As-Mg, 276. C-Fe, 256. 
As-Mn, 279. C-Mn, 255. 
As-Ni, 232. C-Mo, 255. 
As-Pb, 278. C-Ni, 256. 
As-Pt, 283. C-Ti, 255. 
As-S, 290. C-U, 255.. 
As-Sn, 278. C-V, 255. 
As-Te, 310. C-W, 255. 
As-Tl, 278. Ca-Ag, 161. 
As-Zn, 276. Ca-Al, 190. 


Au-Al, 175. 


Ca-Bi, 194. 


Ca-Cd, 115. 
Ca-Cu, 151. 


Ca-Hg, 112. 
Ca-Mg, 113. 
Ca-Pb, 193. 


Ca-Sb, 194. 
Ca-Si, 258. 
Ca-Sn, 1°62. 
Ca-Tl, 191. 


Ca-Zn, 114. 
Cd-Ag, 163. 
Cd-As, 277. 
Cd-Au, 173. 


Cd-Ca, 115. 
Cd-Co, 202. 
Cd-Cr, 291. 
Cd-Cu, 153. 
Cd-Fe, 202. 
Cd-Li, 123: 


Cd-Mg, 109. 
Cd-Na, 129. 


Cd-Ni, 202. 
Cd-P, 269. 

Cd-Sb, 200. 
Cd-Se, 298. 
Cd-Sn, 200. 
Cd-Te, 306. 
Ce-Al, 208. 
Ce-Bi, 231. 


Ce-Mg, 184. 


Ce-Pb, 119. 
Ce-Si, 259. 
Ce-Sn, 117. 
Co-Al, 213. 
Co-As, 281. 
Co-Cd, 202. 
Co-Cr, 247. 
Co-Fe, 121. 


Co-Mo, 248. 


Co-P, 272. 

Co-S, 295. 

Co-Sb, 238. 
Co-Se, 303. 
Co-Si, 264. 
Co-Sn, 226. 
Co-Te, 313. 


Co-Zn, 197. 


Cr-Al, 217. 


OF DINARY oYor EMs, 


Cr-Co, 247. 
Cr-Fe, 246. 
Cr-Hg, 206. 
Cr-Ni, 247. 
Cr-P, 269. 
Cr-Se, 302. 
Cs-Hg, 145. 
Cs-S, 286. 
Cu-Al, 154. 
Cu-As, 275. 
Cu-Ca, 151. 
Cu-Cd, 153. 
Cu-Hg, 154. 
Cu-Mg, 147. 
Cu-P, 267. 
Cu-S, 286. 
Cu-Sb, 158. 
Cu-Se, 296. 
Cu-Si, 256. 
Cu-Sn, 156. 
Cu-Te, 303. 


- Cu-Zn, 156. 


Fe-As, 280. 
Fe-B, 252. 

Fe-Be, 180. 
Fe-C, 256. 

Fe-Cd, 202. 
Fe-Co, 121. 
Fe-Cr, 246. 
Fe-Hg, 208. 
Fe-Mo, 207. 
Fe-Ni, 122. 
Fa-P, 271. 

Fe-S, 293. 

Fe-Sb, 237. 
Fe-Se, 303. 
Fe-Si, 263. 

Fe-Sn, 226. 
Fe-Te, 313. 
Fe-Zn, 196. 


Ga-Hg, 24. 


Hg-Ag, 164. 
Hg-Al, 203. 
Hg-As, 278. 


340 


Hg-Au, 174. 


Hg-Ba, 112. 
Hg-Ca, 112. 
Hg-Cr, 206. 
Hg-Cs, 145. 
Hg-Cu, 154. 
Hg-Fe, 208. 
Hg-Ga, 204. 
Hg-In, 204. 
Hg-K, 139. 
Hg-Li, 125. 


Hg-Mg, 119. 
Hg-Mn, 207. 
Hg-Mo, 207. 


Hg-Na, 129. 
Hg-P, 269. 

Hg-Pt, 208. 
Hg-Rb, 144. 
Hg-Sb, 206. 
Hg-Se, 298. 
Hg-Sn, 205. 
Hg-Sr, 112. 
Hg-Te,'307. 
Hg-TI, 204. 


In-Hg, 204. 
In-S, 288. 
In-Se, 298. 
In-Te, 308. 
Ir-P, 275. 


K-Bi, 143. 
K-Cd, 138. 
K-Hg, 139. 
K-Na, 105. 
K-Pb, 142. 
K-Sb, 143. 
K-Sn, 141. 
K-TI, 140. 
K-Zn, 137. 


La-Al, 117. 
Li-Cd, 123. 
Li-Si, 256. 
Li-5n, 125. 


Mg-Ag, 159. 


Mg-Al, 181. 


Mg-As, 276. 
Mg-Au, 170. 


Mg-Bi, 187. 
Mg-Ca, 113. 
Mg-Cd, 109. 
Mg-Ce, 184. 


Mg-Cu, 147. 
Mg-Hg, 110. 


Mg-Ni, 188. 


Mg-P, 269. 


Mg-Pb, 185. 


Mg-Sb, 186. 
Mg-Si, 258. 
Mg-Sn, 184. 
Mg-TIl, 182. 


Mg-Zn, 108. 
Mn-Ag, 168. 


Mn-Al, 211. 


Mn-As, 279. 
Mn-Au, 179. 


Mn-Bi, 244. 
Mn-C, 255. 


Mn-Hg, 207. 


Mn-P, 270. 
Mn-S, 292. 
Mn-Sb, 236. 
Mn-Se, 303. 
Mn-Si, 262. 


Mn-Sn, 224. 
Mn-Zn, 195. 


Mo-C, 255. 
Mo-Co, 248. 
Mo-Fe, 248. 


- Mo-Hg, 207. 


Mo-Ni, 249. 
Mo -S, 292. 
Mo -Si, 262. 


Na-Au, 106. 


Na-Bi, 136. 
Na-Cd, 129. 
Na-Hg, 129. 
Na-K, 105. 
Na-Pb, 134. 
Na-Sb, 135. 
Na-Sn, 132. 
Na-T]l, 131. 
Na-Zn, 127. 
Ni-Al, 216. 
Ni-As, 282. 
Ni-B, 252. 
Ni-Bi, 246. 
Ni-C, 256. 
Ni-Cd, 202. 
Ni-Cr, 247. 
Ni-Fe, 122. 
Ni-Mg, 188. 
Ni-Mo, 249. 
Ni-P, 273. 
Ni-S, 296. 
Ni-Sb, 239. 
Ni-Se, 303. 
Ni-Si, 265. 
Ni-Sn, 228. 
Ni-Te, 313. 
Ni-Zn, 198. 


P-Ag, 286. 
P-Au, 268. 
P-Bi, 269. 
P-Cd, 269. 
P-Co, 272. 
P-Cr, 269. 
P-Cu, 267. 
P-Fe, 271. 
P-Hg, 269. 
P-Ir, 275. 
P-Mg, 269. 
P-Mn, 270. 
PeNi,27 3: 
P-Pd, 275. 
P-Pt, 275. 
P-Sn, 269. 
P-W, 270. 
P-Zn, 269. 
Pb-As, 278. 
Pb-Au, 177. 
Pb-Ca, 193. 
Pb-Ce, 119. 
Pb-K, 142. 
Pb-Mg, 185. 


Pb-Na, 134.- 


Pb-Pd, 233. 
Pb-Pt, 235. 
Pb-S, 290. 
Pb-Se, 300. 
Pb-Te, 310. 
Pb-Tl, 218. 
Pd-P, 275. 
Pd-Pb, 233. 
Pd-S, 296. 
Pd-Sb, 240. 
Pd-Se, 303. 
Pd-Si, 267. 
Pt-Ag, 169. 
Pt-As, 283. 
Pt-Hg, 208. 
Pt-P, 275. 
Pt-Pb, 235. 
Pt-Se, 393. 
Pt-Sb, 242. 
Pt-Si, 267. 
Pt-Sn, 230. 
Pt-Te, 313. 
Pt-Tl, 222. 


Rb-Hg, 144. 
Rb-S, 284. 
Ru-Si, 267. 


S-Ag, 287. 
S-As, 290. 
S-Au, 287. 


INDEX OF BINARY SYSTEMS. 


S-Bi,{287. 
S-Co, 295. 
S-Cs, 286. 
S-Cu, 286. 
S-Fe, 293. 
S-In, 288. 
S-Mn, 292. 
S-Mo, 292. 
S-Ni, 296. 
S-Pb, 290. 
S-Pd, 296. 
S-Rb, 284. 
S-Se, 292. 
S-Sn, 289. 
S-Tl, 288. 
Sb-Ag, 168. 
Sb-Al, 210. 
Sb-Au, 179. 
Sb-Ca, 194. 
Sb-Cd, 200. 
Sb-Co, 238. 
Sb-Cr, 243. 
Sb-Cu, 158. 
Sb-Fe, 237. 
Sb-Hg, 206. 
Sb-K, 143. 
Sb-Mn, 236. 
Sb-Na, 135. 
Sb-Ni, 239. 
Sb-Pd, 240. 
Sb-Pt, 242. 
Sb-Se, 301. 
Sb-Sn, 223. 
Sb-Te, 311. 
Sb-TI, 219. 
Sb-Zn, 194. 
Se-Ag, 297. 
Se-Bi, 302. 
Se-Cd, 298. 
Se-Co, 303. 
Se-Cr, 302. 
Se-Cu, 296. 
Se-Fe, 303. 
Se-Hg, 298. 
Se-In, 298. 
Se-Mn, 303. 
Se-Ni, 303. 
Se-Pb, 300. 
Se-Pd, 303. 
Se-Pt, 303. 
Se-S, 292. 
Se-Sb, 301. 
Se-Sn, 299. 
Se-Tl, 298. 
Se-Zn, 298. 
Si-Ba, 258. 
Si-Ca, 258. 


Si-Ce, 259. 
Si-Co, 264. 
Si-Cr, 262. 
Si-Cu, 256. 
Si-Fe, 263. 
Si-Li, 256. 


Si-Mg, 258. 
Si-Mn, 262. 
Si-Mo, 262. 


Si-Ni, 265. 
Si-Pd, 267. 
Si-Pt, 267. 
Si-Ru, 267. 
Si-Sr, 258. 
Si-Ta, 262. 
Si-Th, 260. 
Si-Ti, 260. 
Si-U, 262. 
Si-V, 261. 
Si-W, 262. 
Si- Zr, 260. 


Sn-Ag, 167. 
Sn-As, 278. 
Sn-Au, 175. 


Sn-Ca, 192. 
Sn-Cd, 200. 
Sn-Ce, 117. 


Sn-Co, 226. 
Sn-Cu, 156. 
Sn-Fe, 226. 


Sn-Hg, 205. 


Sn-K, 141. 
Sn-Li, 125. 


Sn-Mg, 184. 
Sn-Mn, 224. 


Sn-Na, 132. 
Sn-Ni, 228. 
Sn-P, 269. 

Sn-Pt, 230. 
Sn-S, 289. 

Sn-Sb, 223. 
Sn-Se, 299. 
Sn-Te, 309. 
Sr-Hg, 112. 
Sr-Si, 258. : 


Ta-Si, 262. 


Te-Ag, 304. 


Te-As, olO. 


Te-Au, 305. 


Te-Bi, 312. 
Te-Cd, 306. 
Te-Co, 313. 
Te-Cu, 303. 


Te-Fe, 313. 
Te-Hg, 307. 
Te-In, 308. 
Te-Ni, 313. 
Te-Pb, 310. 
Te-Pt, 313. 
Te-Sb, 311. 


Te-Sn, 309. 


Te-Tl, 308. 
Te-Zn, 306. 
Th-Si, 260. 
Ti-C, 255. 
TI-As, 278. 
TI-Bi, 220. 
Tl-Ca, 191. 
Tl-Hg, 204. 
TI-K, 140. 
TI-Mg, 182. 
Tl-Na, 131. 
Tl-Pb, 218. 
Tl-Pt, 222. 
TI-S, 288. 
TI-Sb, 219. 
Tl-Se, 298. 
Tl-Te, 308. 


U-C, 255. 


INDEX OF BINARY SYSTEMS. 


U-Si, 262. 


V-C, 255. 
V-Si, 261. 


W-C, 255. 
W-Si, 262. — 


Zn-Ag, 162. 
Zn-Al, 194. 
Zn-As, 276. 
Zn-Au, 171. 
Zn-Ca, 114. 
Zn-Co, 197. 
Zn-Cu, 148. 
Zn-Fe, 196. 
Zn-K, 137. 

Zn-Mg, 108. 


Zn-Mn, 195. 


Zn-Na, 127. 
Zn-Ni, 198. 
Zn-P, 269. 

Zn-Sb, 194. 
Zn-Se, 298. 
Zn-Te, 306. 
Zr-Si, 260. 


THE WHITEFRIARS PRESS, LTD., LONDON AND TONBRIDGE, 


341 








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